Inspection device

ABSTRACT

An inspection device for inspecting a surface of an inspection object using a beam includes a beam generator capable of generating one of either charge particles or an electromagnetic wave as a beam, a primary optical system capable of guiding and irradiating the beam to the inspection object supported within a working chamber, a secondary optical system capable of including a first movable numerical aperture and a first detector which detects secondary charge particles generated from the inspection object, the secondary charge particles passing through the first movable numerical aperture, an image processing system capable of forming an image based on the secondary charge particles detected by the first detector; and a second detector arranged between the first movable numerical aperture and the first detector and which detects a location and shape at a cross over location of the secondary charge particles generated from the inspection object.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.13/420,731, filed on Mar. 15, 2012, which is based upon and claims thebenefit of priority from the prior Japanese Patent Application No.2012-15875, filed on 27 Jan. 2012, the prior Japanese Patent ApplicationNo. 2011-57312, filed on 15 Mar. 2011, and the prior Japanese PatentApplication No. 2011-105751, filed on 10 May, 2011, the entire contentsof which are incorporated herein by reference.

FIELD

The present invention relates to an inspection device and methods forinspecting foreign materials, particles, and/or defects in patternsformed on the surface of an object to be inspected, and moreparticularly, to an inspection device and inspection method in whichsecondary electrons which vary in accordance with the properties of thesurface are captured thereof to form image data, and inspecting patternsformed on the surface of the object to be inspected based on the imagedata at a high throughput.

BACKGROUND

Conventional semiconductor inspection devices were compatible with 100mm design rules. However, samples of the object to be inspected arebecoming diversified such as a wafer, exposure mask, EUV mask, NIL (nanoimprint lithography) mask and substrate and presently devices andtechnology which are compatible with sample design rules of 5˜30 nm arebeing demanded. That is, devices and technology in which L/S (linespace) or hp (half pitch) node are in the 5˜30 nm generation are beingdemanded. It is necessary to obtain a high resolution capability wheninspecting such samples using an inspection device.

Here, a sample can be an exposure mask, an EUV mask, a nano print mask(and template) a semiconductor wafer, an optical element substrate, oroptical circuit substrate etc. These are separated into those withpatterns and those without patterns. Those that include patterns arefurther separated into those that have uneven structure and those thatdo not. A pattern that does not include uneven structure is formed usinga different material. Those that do not include patterns are separatedinto those that are coated with an oxide film and those that are notcoated with an oxide film.

Here, the problems associated with inspection devices havingconventional technologies are summarized as follows.

The first problem is related to a deficiency in resolution andthroughput. In the conventional technology of mapping optical systemspixel size was about 50 nm and aberration was about 200 nm. Further, itwas necessary to reduce aberration, reduce the energy width of anirradiation current, reduce pixel size and increase the amount ofcurrent in order to improve high resolution capabilities and throughput.

Secondly, in an SEM type inspection, when objects having a finestructure are increasingly inspected the greater the problem ofthroughput becomes. This is because the image resolution is insufficientif a smaller pixel size is not used. These are the cause of a SEM mainlyforming an image due to edge contrast and performing defect inspection.For example, an inspection requires 6 hr/cm2 at 5 nmPx size and 200MPPS. This would require 20˜50 times the amount of time required for amapping projection type which is unrealistic for an inspection.International Publication WO20002/001596, Japanese Laid Open Patent No.2007-48686, and Japanese Laid Open Patent H11-132975 are referred to asconventional technology.

SUMMARY

Thus, the present invention aims to provide an inspection method and aninspection device which solves the defects of a conventional inspectiondevice described above, can improve inspection accuracy and can beapplied to 5˜30 nm design rules.

In addition, according to one embodiment of the present invention, aninspection device for inspecting a surface of an inspection object usinga beam is provide including a beam generator which is capable ofgenerating one of either charge particles or an electromagnetic wave asa beam, a primary optical system which is capable of guiding andirradiating the beam to the inspection object supported within a workingchamber, a secondary optical system which is capable of including afirst movable numerical aperture and a first detector which detectssecondary charge particles generated from the inspection object, thesecondary charge particles passing through the first movable numericalaperture, an image processing system which is capable of forming animage based on the secondary charge particles detected by the firstdetector, and a second detector arranged between the first movablenumerical aperture and the first detector and which detects a locationand shape at a cross over location of the secondary charge particlesgenerated from the inspection object.

The first detector may detect the secondary charge particles in a statewhere the location of the first movable numerical aperture is adjustedbased on a detection result of the second detector.

The beam may be a beam of charged particles, and the beam generator mayinclude a photoelectron element formed by coating a photoelectronmaterial on a planar part of a base material comprised from atransmittance part including the planar part, the photoelectron elementreceiving light irradiated from the photoelectron material to generatephotoelectrons, one or more lenses each arranged at a predeterminedintervals after the photoelectron element respectively, the one or morelenses accelerating photoelectrons generated from the photoelectronelement, a second numerical aperture arranged on the lower side of theone or more lenses, and a cathode lens arranged after the numericalaperture.

The beam may be an electromagnetic wave beam, the beam generator maygenerate a plurality of beams with different wavelengths.

The first detector may detect the secondary charge particles generatedfrom a surface of the inspection object irradiated with the beam.

The first detector may detect the secondary charge particles generatedfrom a surface opposite a surface of the inspection object irradiatedwith the beam.

The first detector may include a TDI.

The second detector may include an EB-CDD.

The first movable numerical aperture may include an open part formed bya plus shape or slit.

The inspection device 1 may further include an optical microscope and aSEM (scanning type electron microscope) which observes the inspectionobject, wherein the beam generator, the primary optical system, thesecondary optical system, the image processing system, the opticalmicroscope and the SEM are arranged in the working chamber.

The secondary charge particles described above may be a part of or amixture of secondary emission electrons, mirror electrons andphotoelectrons. Photoelectrons are generated from a sample surface whenan electromagnetic wave is irradiated. Secondary emission electrons aregenerated when charge particles such an electron beam is irradiated to asample surface. Alternatively, mirror electrons are formed. Secondaryemission electrons are generated when an electron beam collides with asample surface. That is, secondary emission electrons are a part of ormixture of secondary electrons, reflected electrons and back scatteredelectrons. In addition, electrons reflected near a surface where anirradiated electron beam does not collide with a sample surface arecalled mirror electrons.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an elevated view diagram which shows the main structuralelements of an inspection device of the present invention related to oneembodiment, seen along the line A-A in FIG. 2;

FIG. 2A is a planar view diagram of the main structural elements of theinspection device shown in FIG. 1, seen along the line B-B in FIG. 1;

FIG. 2B is an approximate cross-sectional diagram which shows anotherexample of a substrate transfer device in the inspection device of thepresent invention related to one embodiment;

FIG. 3 is a cross-sectional diagram which shows the mini environment inFIG. 1 seen along the line C-C;

FIG. 4 is a diagram which shows the loader housing in FIG. 1 seen alongthe line D-D in FIG. 2;

FIG. 5 is an expanded view diagram of a wafer rack, [A] is a side viewdiagram and [B] is a cross-sectional view diagram seen along the lineE-E of [A];

FIG. 6 is a diagram which shows modifications of a method for supportinga main housing;

FIG. 7 is a diagram which shows modifications of a method for supportinga main housing;

FIG. 8 is a schematic diagram which shows an approximate structure of anelectron optical device of the inspection device in FIG. 1;

FIG. 9 is a diagram related to one embodiment of the present invention;

FIG. 10 is a diagram related to one embodiment of the present invention;

FIG. 11 is a diagram related to one embodiment of the present invention;

FIG. 12 is a diagram related to one embodiment of the present invention;

FIG. 13 is a diagram related to one embodiment of the present invention;

FIG. 14 is a diagram related to one embodiment of the present invention;

FIG. 15 is a diagram related to one embodiment of the present invention;

FIG. 16 is a diagram related to one embodiment of the present invention;

FIG. 17 is a diagram related to one embodiment of the present invention;

FIG. 18 is a diagram related to one embodiment of the present invention;

FIG. 19 is a diagram related to one embodiment of the present invention;

FIG. 20 is a diagram related to one embodiment of the present invention;

FIG. 21 is a diagram related to one embodiment of the present invention;

FIG. 22 is a diagram related to one embodiment of the present invention;

FIG. 23 is a diagram related to one embodiment of the present invention;

FIG. 24 is a diagram related to one embodiment of the present invention;

FIG. 25 is a diagram related to one embodiment of the present invention;

FIG. 26A is a diagram related to one embodiment of the presentinvention;

FIG. 26B is a diagram related to one embodiment of the presentinvention;

FIG. 26C is a diagram related to one embodiment of the presentinvention;

FIG. 27A is a diagram related to one embodiment of the presentinvention;

FIG. 27B is a diagram related to one embodiment of the presentinvention;

FIG. 28 is a diagram related to one embodiment of the present invention;

FIG. 29A is a diagram related to one embodiment of the presentinvention;

FIG. 29B is a diagram related to one embodiment of the presentinvention;

FIG. 30 is a diagram related to one embodiment of the present invention;

FIG. 31 is a diagram related to one embodiment of the present invention;

FIG. 32A is a diagram related to one embodiment of the presentinvention;

FIG. 32B is a diagram related to one embodiment of the presentinvention;

FIG. 32C is a diagram related to one embodiment of the presentinvention;

FIG. 32D is a diagram related to one embodiment of the presentinvention;

FIG. 32E is a diagram related to one embodiment of the presentinvention;

FIG. 33 is a diagram related to one embodiment of the present invention;

FIG. 34 is a diagram related to one embodiment of the present invention;

FIG. 35 is a diagram related to one embodiment of the present invention;

FIG. 36 is a diagram related to one embodiment of the present invention;

FIG. 37 is a diagram related to one embodiment of the present invention;

FIG. 38 is a diagram related to one embodiment of the present invention;

FIG. 39 is a diagram related to one embodiment of the present invention;

FIG. 40 is a diagram related to one embodiment of the present invention;

FIG. 41 is a diagram related to one embodiment of the present invention;

FIG. 42 is a diagram related to one embodiment of the present invention;

FIG. 43 is a diagram related to one embodiment of the present invention;

FIG. 44 is a diagram related to one embodiment of the present invention;

FIG. 45 is a diagram related to one embodiment of the present invention;

FIG. 46 is a diagram related to one embodiment of the present invention;

FIG. 47 is a diagram related to one embodiment of the present invention;

FIG. 48 is a diagram related to one embodiment of the present invention;

FIG. 49 is a diagram related to one embodiment of the present invention;

FIG. 50 is a diagram related to one embodiment of the present invention;

FIG. 51 is a diagram related to one embodiment of the present invention;

FIG. 52 is a diagram related to one embodiment of the present invention;

FIG. 53 is a diagram related to one embodiment of the present invention;

FIG. 54 is a diagram related to one embodiment of the present invention;

FIG. 55 is a diagram related to one embodiment of the present invention;

FIG. 56 is a diagram related to one embodiment of the present invention;

FIG. 57 is a diagram related to one embodiment of the present invention;

FIG. 58 is a diagram related to one embodiment of the present invention;

FIG. 59 is a diagram related to one embodiment of the present invention;

FIG. 60 is a diagram related to one embodiment of the present invention;

FIG. 61 is a diagram related to one embodiment of the present invention;

FIG. 62 is a diagram related to one embodiment of the present invention;

FIG. 63 is a diagram related to one embodiment of the present invention;

FIG. 64 is a diagram related to one embodiment of the present invention;

FIG. 65 is a diagram related to one embodiment of the present invention;

FIG. 66 is a diagram related to one embodiment of the present invention;

FIG. 67 is a diagram related to one embodiment of the present invention;

FIG. 68 is a diagram related to one embodiment of the present invention;

FIG. 69 is a diagram related to one embodiment of the present invention;

FIG. 70 is a diagram related to one embodiment of the present invention;

FIG. 71 is a diagram related to one embodiment of the present invention;

FIG. 72 is a diagram related to one embodiment of the present invention;

FIG. 73 is a diagram related to one embodiment of the present invention;

FIG. 74 is a diagram related to one embodiment of the present invention;

FIG. 75 is a diagram related to one embodiment of the present invention;

FIG. 76 is a diagram related to one embodiment of the present invention;

FIG. 77 is a diagram related to one embodiment of the present invention;

FIG. 78 is a diagram related to one embodiment of the present invention;

FIG. 79 is a diagram related to one embodiment of the present invention;

FIG. 80 is a diagram related to one embodiment of the present invention;

FIG. 81 is a diagram related to one embodiment of the present invention;

FIG. 82 is a diagram related to one embodiment of the present invention;

FIG. 83 is a diagram related to one embodiment of the present invention;

FIG. 84 is a diagram related to one embodiment of the present invention;

FIG. 85 is a diagram related to one embodiment of the present invention;

FIG. 86 is a diagram related to one embodiment of the present invention;

FIG. 87 is a diagram related to one embodiment of the present invention;

FIG. 88 is a diagram related to one embodiment of the present invention;

FIG. 89 is a diagram related to one embodiment of the present invention;

FIG. 90 is a diagram related to one embodiment of the present invention;

FIG. 91 is a diagram related to one embodiment of the present invention;

FIG. 92 is a diagram related to one embodiment of the present invention;

FIG. 93 is a diagram related to one embodiment of the present invention;

FIG. 94 is a diagram related to one embodiment of the present invention;

FIG. 95 is a diagram related to one embodiment of the present invention;

FIG. 96A is a diagram related to one embodiment of the presentinvention;

FIG. 96B is a diagram related to one embodiment of the presentinvention;

FIG. 97 is a diagram related to one embodiment of the present invention;

FIG. 98 is a diagram related to one embodiment of the present invention;

FIG. 99 is a diagram related to one embodiment of the present invention;

FIG. 100 is a diagram related to one embodiment of the presentinvention;

FIG. 101 is a diagram related to one embodiment of the presentinvention;

FIG. 102 is a diagram related to one embodiment of the presentinvention;

FIG. 103 is a diagram related to one embodiment of the presentinvention;

FIG. 104 is a diagram related to one embodiment of the presentinvention;

FIG. 105 is a diagram related to one embodiment of the presentinvention;

FIG. 106 is a diagram related to one embodiment of the presentinvention;

FIG. 107 is a diagram related to one embodiment of the presentinvention;

FIG. 108 is a diagram related to one embodiment of the presentinvention;

FIG. 109 is a diagram related to one embodiment of the presentinvention;

FIG. 110 is a diagram related to one embodiment of the presentinvention;

FIG. 111 is a diagram related to one embodiment of the presentinvention;

FIG. 112 is a diagram related to one embodiment of the presentinvention;

FIG. 113 is a diagram related to one embodiment of the presentinvention;

FIG. 114 is a diagram related to one embodiment of the presentinvention;

FIG. 115 is a diagram related to one embodiment of the presentinvention;

FIG. 116 is a diagram related to one embodiment of the presentinvention;

FIG. 117 is a diagram related to one embodiment of the presentinvention;

FIG. 118 is a diagram related to one embodiment of the presentinvention;

FIG. 119 is a diagram related to one embodiment of the presentinvention;

FIG. 120 is a diagram related to one embodiment of the presentinvention;

FIG. 121 is a diagram related to one embodiment of the presentinvention;

FIG. 122 is a diagram related to one embodiment of the presentinvention;

FIG. 123 is a diagram related to one embodiment of the presentinvention;

FIG. 124 is a diagram related to one embodiment of the presentinvention;

FIG. 125 is a diagram related to one embodiment of the presentinvention;

FIG. 126 is a diagram related to one embodiment of the presentinvention;

FIG. 127 is a diagram related to one embodiment of the presentinvention;

FIG. 128 is a diagram related to one embodiment of the presentinvention;

FIG. 129 is a diagram related to one embodiment of the presentinvention;

FIG. 130 is a diagram related to one embodiment of the presentinvention;

FIG. 131 is a diagram related to one embodiment of the presentinvention;

FIG. 132 is a diagram related to one embodiment of the presentinvention;

FIG. 133 is a diagram related to one embodiment of the presentinvention;

FIG. 134 is a diagram related to one embodiment of the presentinvention;

FIG. 135 is a diagram related to one embodiment of the presentinvention;

FIG. 136 is a diagram related to one embodiment of the presentinvention;

FIG. 137 is a diagram related to one embodiment of the presentinvention;

FIG. 138 is a diagram related to one embodiment of the presentinvention;

FIG. 139 is a diagram related to one embodiment of the presentinvention;

FIG. 140 is a diagram related to one embodiment of the presentinvention;

FIG. 141 is a diagram related to one embodiment of the presentinvention;

FIG. 142 is a diagram related to one embodiment of the presentinvention;

FIG. 143 is a diagram related to one embodiment of the presentinvention;

FIG. 144 is a diagram related to one embodiment of the presentinvention;

FIG. 145A is a diagram related to one embodiment of the presentinvention;

FIG. 145B is a diagram related to one embodiment of the presentinvention;

FIG. 145C is a diagram related to one embodiment of the presentinvention;

FIG. 146A is a diagram related to one embodiment of the presentinvention;

FIG. 146B is a diagram related to one embodiment of the presentinvention;

FIG. 147A is a diagram related to one embodiment of the presentinvention;

FIG. 147B is a diagram related to one embodiment of the presentinvention;

FIG. 148A is a diagram related to one embodiment of the presentinvention;

FIG. 148B is a diagram related to one embodiment of the presentinvention;

FIG. 148C is a diagram related to one embodiment of the presentinvention;

FIG. 149A is a diagram related to one embodiment of the presentinvention;

FIG. 149B is a diagram related to one embodiment of the presentinvention;

FIG. 150 is a diagram related to one embodiment of the presentinvention;

FIG. 151A is a diagram related to one embodiment of the presentinvention;

FIG. 151B is a diagram related to one embodiment of the presentinvention;

FIG. 152 is a diagram related to one embodiment of the presentinvention;

FIG. 153A is a diagram related to one embodiment of the presentinvention;

FIG. 153B is a diagram related to one embodiment of the presentinvention;

FIG. 154 is a diagram related to one embodiment of the presentinvention;

FIG. 155 is a diagram related to one embodiment of the presentinvention;

FIG. 156 is a diagram related to one embodiment of the presentinvention;

FIG. 157A is a diagram related to one embodiment of the presentinvention;

FIG. 157B is a diagram related to one embodiment of the presentinvention;

FIG. 157C is a diagram related to one embodiment of the presentinvention;

FIG. 158 is a diagram related to one embodiment of the presentinvention;

FIG. 159 is a diagram related to one embodiment of the presentinvention;

FIG. 160A is a diagram related to one embodiment of the presentinvention;

FIG. 160B is a diagram related to one embodiment of the presentinvention;

FIG. 161 is a diagram related to one embodiment of the presentinvention;

FIG. 162A is a diagram related to one embodiment of the presentinvention;

FIG. 162B is a diagram related to one embodiment of the presentinvention;

FIG. 163 is a diagram related to one embodiment of the presentinvention;

FIG. 164 is a diagram related to one embodiment of the presentinvention;

FIG. 165 is a diagram related to one embodiment of the presentinvention;

FIG. 166 is a diagram related to one embodiment of the presentinvention;

FIG. 167 is a diagram related to one embodiment of the presentinvention;

FIG. 168 is a diagram related to one embodiment of the presentinvention;

FIG. 169 is a diagram related to one embodiment of the presentinvention;

FIG. 170 is a diagram related to one embodiment of the presentinvention;

FIG. 171 is a diagram related to one embodiment of the presentinvention;

FIG. 172 is a diagram related to one embodiment of the presentinvention;

FIG. 173 is a diagram related to one embodiment of the presentinvention;

FIG. 174 is a diagram related to one embodiment of the presentinvention;

FIG. 175 is a diagram related to one embodiment of the presentinvention;

FIG. 176 is a diagram related to one embodiment of the presentinvention;

FIG. 177 is a diagram related to one embodiment of the presentinvention;

FIG. 178 is a diagram related to one embodiment of the presentinvention;

FIG. 179 is a diagram related to one embodiment of the presentinvention;

FIG. 180 is a diagram related to one embodiment of the presentinvention;

FIG. 181 is a diagram related to one embodiment of the presentinvention;

FIG. 182 is a diagram related to one embodiment of the presentinvention;

FIG. 183 is a diagram related to one embodiment of the presentinvention;

FIG. 184 is a diagram related to one embodiment of the presentinvention;

FIG. 185 is a diagram related to one embodiment of the presentinvention;

FIG. 186 is a diagram related to one embodiment of the presentinvention;

FIG. 187 is a diagram related to one embodiment of the presentinvention;

FIG. 188 is a diagram related to one embodiment of the presentinvention;

FIG. 189 is a diagram related to one embodiment of the presentinvention;

FIG. 190 is a diagram related to one embodiment of the presentinvention;

FIG. 191 is a diagram related to one embodiment of the presentinvention;

FIG. 192 is a diagram related to one embodiment of the presentinvention;

FIG. 193 is a diagram related to one embodiment of the presentinvention;

FIG. 194A is a diagram related to one embodiment of the presentinvention;

FIG. 194B is a diagram related to one embodiment of the presentinvention;

FIG. 195A is a diagram related to one embodiment of the presentinvention;

FIG. 195B is a diagram related to one embodiment of the presentinvention;

FIG. 196 is a diagram related to one embodiment of the presentinvention;

FIG. 197 is a diagram related to one embodiment of the presentinvention;

FIG. 198 is a diagram related to one embodiment of the presentinvention;

FIG. 199 is a diagram related to one embodiment of the presentinvention;

FIG. 200 is a diagram related to one embodiment of the presentinvention;

FIG. 201 is a diagram related to one embodiment of the presentinvention;

FIG. 202 is a diagram related to one embodiment of the presentinvention;

FIG. 203 is a diagram related to one embodiment of the presentinvention;

FIG. 204 is a diagram related to one embodiment of the presentinvention;

FIG. 205 is a diagram related to one embodiment of the presentinvention;

FIG. 206 is a diagram related to one embodiment of the presentinvention;

FIG. 207 is a diagram related to one embodiment of the presentinvention;

FIG. 208 is a diagram related to one embodiment of the presentinvention;

FIG. 209 is a diagram related to one embodiment of the presentinvention;

FIG. 210 is a diagram related to one embodiment of the presentinvention;

FIG. 211 is a diagram related to one embodiment of the presentinvention;

FIG. 212 is a diagram related to one embodiment of the presentinvention;

FIG. 213 is a diagram related to one embodiment of the presentinvention;

FIG. 214 is a diagram related to one embodiment of the presentinvention;

FIG. 215 is a diagram related to one embodiment of the presentinvention;

FIG. 216 is a diagram related to one embodiment of the presentinvention;

FIG. 217 is a diagram related to one embodiment of the presentinvention;

FIG. 218 is a diagram related to one embodiment of the presentinvention;

FIG. 219 is a diagram related to one embodiment of the presentinvention;

FIG. 220 is a diagram related to one embodiment of the presentinvention;

FIG. 221 is a diagram related to one embodiment of the presentinvention;

FIG. 222 is a diagram related to one embodiment of the presentinvention;

FIG. 223 is a diagram related to one embodiment of the presentinvention; and

FIG. 224 is a diagram related to one embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present invention will be explained using asubstrate formed with a pattern on the surface as an object ofinspection, that is, as a semiconductor inspection device for inspectinga wafer while referring to the diagrams. According to the presentinvention, it is possible to provide an inspection method and aninspection device in which inspection accuracy is improved. Furthermore,the embodiments herein are examples of the inspection device andinspection method of the present invention and are not limited to theseexamples.

An elevated view and a planar view of the main structural elements of asemiconductor inspection device 1 of the present embodiment, are shownin FIG. 1 and FIG. 2A.

The semiconductor inspection apparatus 1 of the present embodimentcomprises a cassette holder 10 for holding cassettes which store aplurality of wafers; a mini-environment chamber 20; a main housing 30which defines a working chamber; a loader housing 40 disposed betweenthe mini-environment chamber 20 and the main housing 30 to define twoloading chambers; a loader 60 for loading a wafer from the cassetteholder 10 onto a stage device 50 disposed in the main housing 30; anelectron-optical device 70 installed in a vacuum housing 30; and ascanning type electron microscope (SEM) 3002. These components arearranged in a positional relationship as illustrated in FIGS. 1 and 2A.The semiconductor inspection apparatus 1 further comprises a prechargeunit 81 disposed in the vacuum main housing 30; a potential applyingmechanism 83 (see in FIG. 14) for applying potential to a wafer; anelectron beam calibration mechanism 85 (see in FIG. 15); and an opticalmicroscope 871 which forms part of an alignment controller 87 foraligning the wafer on the stage device 50. The electron-optical device70 includes a lens column 71 and a light source column 7000. Theinternal structure of the electron-optical device 70 is described below.

Cassette Holder

The cassette holder 10 is configured to hold a plurality (two in thisembodiment) of cassettes c (for example, closed cassettes such as SMIF,FOUP manufactured by Assist Co.) in which a plurality (for example, 25)of wafers are stacked in parallel in the vertical direction. Thecassette holder 10 can be arbitrarily selected for installation adaptedto a particular loading mechanism. Specifically, when a cassette,carried to the cassette holder 10, is automatically loaded into thecassette holder 10 by a robot or the like, the cassette holder 10 havinga structure adapted to the automatic loading can be installed. When acassette is manually loaded into the cassette holder 10, the cassetteholder 10 having an open cassette structure can be installed. In thisembodiment, the cassette holder 10 is of a type adapted to the automaticcassette loading, and comprises, for example, an up/down table 11, andan elevating mechanism 12 for moving the up/down table 11 up and down.The cassette c can be automatically set onto the up/down table 11 in astate indicated by chain lines in FIG. 2A. After the setting, thecassette c is automatically rotated to a state indicated by solid linesin FIG. 2A so that it is directed to the axis of pivotal movement of afirst carrier unit within the mini-environment chamber 20. In addition,the up/down table 11 is moved down to a state indicated by chain linesin FIG. 1. In this way, the cassette holder 10 for use in automaticloading, or the cassette holder 10 for use in manual loading may beconfigured in known structures, so that detailed description on theirstructures and functions are omitted.

In another embodiment, as shown in FIG. 2B, a plurality of 300 mmsubstrates is accommodated so that each is contained in a slot-likepocket fixedly mounted in an inner side of a box main body 501 so as tobe transferred and stored. This substrate carrier box 24 is composed ofa box main body 501 of cylinder with angular section, a door 502 forcarrying the substrate in and out, which is coupled with an automaticopening/closing unit of the door for carrying the substrate in and outso as to be capable of mechanically opening and closing an opening in aside face of the box main body 501, a lid body 503 disposed in anopposite side of said opening, for covering another opening throughwhich filters and a fan motor are to be attached or detached, aslot-like pocket (not shown in the diagram) for holding a substrate W, aULPA filter 505, a chemical filter 506, and a fan motor 507. In thisembodiment, the substrate is carried in or out by a first carrier unit612 of robot type in a loader 60.

It should be noted that substrates, that is, wafers accommodated in thecassette c are wafers subjected to inspecting which is generallyperformed after a process for processing the wafers or in the middle ofthe process within a semiconductor manufacturing processes.Specifically, accommodated in the cassette are substrates or waferswhich have undergone a deposition process, CMP, ion implantation and soon; wafers with circuit patterns on the surface thereof; or wafers whichhave not been formed with circuit patterns. Since a large number ofwafers accommodated in the cassette c are spaced from each other in thevertical direction and arranged in parallel, the first carrier unit hasan arm which is vertically movable such that a wafer at an arbitraryposition can be held by the first carrier unit, as described later indetail.

Mini-Environment Chamber

In FIG. 1 through 3, the mini-environment chamber 20 comprises a housing22 which defines a mini-environment space 21 with a controlledatmosphere; a gas circulator 23 for circulating a gas such as clean airwithin the mini-environment space 21 for the atmosphere control; adischarger 24 for recovering a portion of air supplied into themini-environment space 21 for discharging; and a prealigner 25 forroughly aligning a substrate, i.e., a wafer to be inspected, which isplaced in the mini-environment space 21.

The housing 22 has a top wall 221, a bottom wall 222, and peripheralwall(s) 223 which surrounds four sides of the housing 22 to provide astructure for isolating the mini-environment space 21 from the outside.For controlling the atmosphere in the mini-environment space 21, the gascirculator 23 comprises a gas supply unit 231 attached to the top wall221 within the mini-environment space 21 as illustrated in FIG. 3 forcleaning a gas (air in this embodiment) and delivering the cleaned gasdownward through one or more gas nozzles (not shown in the diagram) inlaminar flow; a recovery duct 232 disposed on the bottom wall 222 withinthe mini-environment space for recovering air which has flowed to thebottom; and a conduit 233 for connecting the recovery duct 232 to thegas supply unit 231 for returning recovered air to the gas supply unit231. In this embodiment, the gas supply unit 231 constantly replacesabout 20% of air to be supplied, with the air taken from the outside ofthe housing 22 for cleaning. However, the percentage of gas taken fromthe outside may be arbitrarily selected. The gas supply unit 231comprises a HEPA or ULPA filter of a known structure for creatingcleaned air. The laminar downflow of cleaned air is mainly supplied suchthat the air passes a carrying surface of the first carrier unit 61,later described, disposed within the mini-environment space 21 toprevent dust particles, which could be produced by the carrier unit,from attaching to the wafer. Therefore, the downflow nozzles need not bepositioned near the top wall as illustrated, but are only required to beabove the carrying surface of the carrier unit 61. In addition, the airneed not be supplied over the entire mini-environment space 21. Itshould be noted that an ion wind may be used as cleaned air to ensurethe cleanliness as the case may be. Also, a sensor may be providedwithin the mini-environment space 21 for observing the cleanliness suchthat the apparatus is shut down when the cleanliness is below apredetermined level. An access port 225 is formed in a portion of theperipheral wall 223 of the housing 22 that is adjacent to the cassetteholder 10. A shutter device of a known structure may be provided nearthe access port 225 to shut the access port 225 from themini-environment chamber 20. The laminar downflow near the wafer may be,for example, at a rate of 0.3 to 0.4 m/sec. The gas supply unit 231 maybe disposed outside the mini-environment space 21 instead of within themini-environment space 21.

The discharger 24 comprises a suction duct 241 disposed at a positionbelow the wafer carrying surface of the carrier unit 61 and below thecarrier unit 61; a blower 242 disposed outside the housing 22; and aconduit 243 for connecting the suction duct 241 to the blower 242. Thedischarger 24 sucks a gas flowing down around the carrier unit andincluding dust, which could be produced by the carrier unit, through thesuction duct 241, and discharges the gas outside the housing 22 throughthe conduits 243, 244 and the blower 242. In this event, the gas may bedischarged into an exhaust pipe (not shown in the diagram) which is laidto the vicinity of the housing 22.

The aligner 25 disposed within the mini-environment space 21 opticallyor mechanically detects an orientation flat (which refers to a flatportion formed along the outer periphery of a circular wafer) formed onthe wafer, or one or more V-shaped notches formed on the outerperipheral edge of the wafer to previously align the orientation of thewafer in a rotating direction about the axis of the wafer at an accuracyof approximately ±one degree. The prealigner forms part of a mechanismfor determining the coordinates of an object to be inspected, which is afeature of the claimed invention, and is responsible for rough alignmentof an object to be inspected. Since the pre-aligner itself may be of aknown structure, description on its structure and operation is omitted.

Though not shown in the diagram, a recovery duct for the discharger 24may also be provided below the pre-aligner such that air including dust,discharged from the pre-aligner, is discharged to the outside.

Main Housing

In FIGS. 1 and 2, the main housing 30, which defines the working chamber31, comprises a housing body 32 that is supported by a housingsupporting device 33 carried on a vibration isolator 37 disposed on abase frame 36. The housing supporting device 33 comprises a framestructure 331 assembled into a rectangular form. The housing body 32comprises a bottom wall 321 securely carried on the frame structure 331;a top wall 322; and a peripheral wall 323 which is connected to thebottom wall 321 and the top wall 322 and surrounds four sides of thehousing body 32, and isolates the working chamber 31 from the outside.In this embodiment, the bottom wall 321 is made of a relatively thicksteel plate to prevent distortion due to the weight of equipment carriedthereon such as the stage device 50. Alternatively, another structuremay be employed. In this embodiment, the housing body 32 and the housingsupporting device 33 are assembled into a rigid construction, and thevibration isolator 37 blocks vibrations from the floor, on which thebase frame 36 is installed, from being transmitted to the rigidstructure. A portion of the peripheral wall 323 of the housing body 32that adjoins the loader housing 40, later described, is formed with anaccess port 325 for introducing and removing a wafer.

The vibration isolator 37 may be either of an active type which has anair spring, a magnetic bearing and so on, or a passive type likewisehaving these components. Since any known structure may be employed forthe vibration isolator 37, description on the structure and functions ofthe vibration isolator itself is omitted. The working chamber 31 is heldin a vacuum atmosphere by a vacuum system (not shown in the diagram) ofa known structure. A controller 2 for controlling the operation of theoverall apparatus is disposed below the base frame 36.

Loader Housing

In FIGS. 1, 2 and 4, the loader housing 40 comprises a housing body 43which defines a first loading chamber 41 and a second loading chamber42. The housing body 43 comprises a bottom wall 431; a top wall 432; aperipheral wall 433 which surrounds four sides of the housing body 43;and a partition wall 434 for partitioning the first loading chamber 41and the second loading chamber 42 such that both the loading chamberscan be isolated from the outside. The partition wall 434 is formed withan opening, i.e., an access port 435 for passing a wafer between boththe loading chambers. Also, a portion of the peripheral wall 433 thatadjoins the mini-environment device 20 and the main housing 30 is formedwith access ports 436, 437. The housing body 43 of the loader housing 40is carried on and supported by the frame structure 331 of the housingsupporting device 33. This prevents vibrations from the floor from beingtransmitted to the loader housing 40 as well. The access port 436 of theloader housing 40 is in alignment with the access port 226 of thehousing 22 of the mini-environment device 20, and a shutter device 27 isprovided for selectively blocking communication between themini-environment space 21 and the first loading chamber 41. The shutterdevice 27 has a sealing material 271 which surrounds the peripheries ofthe access ports 226, 436 and is fixed to the side wall 433 in closecontact therewith; a door 272 for blocking air from flowing through theaccess ports in cooperation with the sealing material 271; and a driver273 for moving the door 272. Likewise, the access port 437 of the loaderhousing 40 is in alignment with the access port 325 of the housing body32, and a shutter 45 is provided for selectively blocking communicationbetween the second loading chamber 42 and the working chamber 31 in ahermetic manner. The shutter 45 comprises a sealing material 451 whichsurrounds the peripheries of the access ports 437, 325 and is fixed toside walls 433, 323 in close contact therewith; a door 452 for blockingair from flowing through the access ports in cooperation with thesealing material 451; and a driver 453 for moving the door 452. Further,the opening 435 formed through the partition wall 434 is provided with ashutter 46 for closing the opening with the door 461 to selectivelyblocking communication between the first and second loading chambers ina hermetic manner. These shutter devices 27, 45, 46 are configured toprovide air-tight sealing for the respective chambers when they are in aclosed state. Since these shutter devices may be implemented by knownones, detailed description of their structures and operations isomitted. It should be noted that the method of supporting the housing 22of the mini-environment device 20 is different from the method ofsupporting the loader housing 40. Therefore, for preventing vibrationsfrom being transmitted from the floor through the minienvironment device20 to the loader housing 40 and the main housing 30, a vibration-proofcushion material may be disposed between the housing 22 and the loaderhousing 40 to provide air-tight sealing for the peripheries of theaccess ports.

Within the first loading chamber 41, a wafer rack 47 is disposed forsupporting a plurality (two in this embodiment) of wafers spaced in thevertical direction and maintained in a horizontal state. As illustratedin FIG. 5, the wafer rack 47 comprises posts 472 fixed at four cornersof a rectangular base plate 471, spaced from one another, in an uprightstate. Each of the posts 472 is formed with supporting portions 473, 474in two stages, such that peripheral edges of wafers W are carried on andheld by these supporting portions. Then, leading ends of arms of thefirst and second carrier units 61, 63, later described, are broughtcloser to wafers from adjacent posts and grasp the wafers.

The atmosphere of the loading chambers 41, 42 can be controlled so as tobe maintained in a high vacuum state (at a vacuum degree of 10⁻⁵ to 10⁻⁶Pa) by a vacuum evacuator (not shown in the diagram) in a knownstructure including a vacuum pump, not shown. In this event, the firstloading chamber 41 may be held in a low vacuum atmosphere as a lowvacuum chamber, while the second loading chamber 42 may be held in ahigh vacuum atmosphere as a high vacuum chamber, to effectively preventcontamination of wafers. The employment of such a structure allows awafer, which is accommodated in the loading chamber and is nextsubjected to the defect inspection, to be carried into the workingchamber without delay. The employment of such a loading chambersprovides for an improved throughput for the defect inspection, and thehighest possible vacuum state around the electron beam source which isrequired to be kept in a high vacuum state.

The first and second loading chambers 41, 42 are connected to a vacuumexhaust pipe and a vent pipe for an inert gas (for example, dried purenitrogen) (neither of which are shown in the diagram), respectively. Inthis way, the atmospheric state within each loading chamber is attainedby an inert gas vent (which injects an inert gas to prevent oxygen andnon-inert gases from contacting the surface). Since an apparatus itselffor implementing the inert gas vent is known in structure, detaileddescription thereon is omitted.

Stage Device

The stage device 50 comprises a fixed table 51 disposed on the bottomwall 321 of the main housing 30; a Y-table 52 movable in the Y-directionon the fixed table 51 (the direction vertical to the drawing sheet inFIG. 1); an X-table 53 movable in the X-direction on the Y-table 52 (inthe left-to-right direction in FIG. 1); a turntable 54 rotatable on theX-table; and a holder 55 disposed on the turntable 54. A wafer W isreleasably held on a wafer carrying surface 551 of the holder 55. Theholder 55 may be of a known structure which is capable of releasablyholding a wafer by means of a mechanical or electrostatic chuck feature.The stage device 50 uses servo motors, encoders and a variety of sensors(not shown) to operate a plurality of tables as mentioned above topermit highly accurate alignment of a wafer W held on the carryingsurface 551 by the holder 55 in the X-direction, Y-direction andZ-direction (in the up-down direction in FIG. 1) with respect to anelectron beam irradiated from the electron-optical system 70, and in adirection about the axis normal to the wafer supporting surface (θdirection). The alignment in the Z-direction may be made such that theposition on the carrying surface 551 of the holder 55, for example, canbe finely adjusted in the Z-direction. In this event, a referenceposition on the carrying surface 551 is sensed by a position measuringdevice using a laser of small diameter (a laser interference rangefinder using the principles of an interferometer) to control theposition by a feedback circuit, which is not shown in the diagram.Additionally or alternatively, the position of a notch or theorientation flat of a wafer is measured to sense the plane position andthe rotational position of the wafer relative to the electron beam tocontrol the position of the wafer by rotating the turntable 54 by astepping motor which can be controlled in extremely small angularincrements. In order to maximally prevent dust produced within theworking chamber, servo motors 521, 531 and encoders 522, 532 for thestage device 50 are disposed outside the main housing 30. Since thestage device 50 may be of a known structure used, for example, insteppers and so on, detailed description of its structure and operationis omitted. Likewise, since the laser interference range finder may alsobe of a known structure, detailed description of its structure andoperation is also omitted.

It is also possible to establish a basis for signals which are generatedby previously inputting a rotational position, and X-, Y-positions of awafer relative to the electron beam in a signal detecting system or animage processing system, later described. The wafer chucking mechanismprovided in the holder 55 is configured to apply a voltage for chuckinga wafer to an electrode of an electrostatic chuck, and the alignment ismade by holding three points on the outer periphery of the wafer(preferably spaced equally in the circumferential direction). The waferchucking mechanism comprises two fixed aligning pins and a push-typeclamp pin. The clamp pin can realize automatic chucking and automaticreleasing, and constitutes an electric conducting portion for applyingthe voltage.

While in this embodiment, the X-table is defined as a table which ismovable in the left-to-right or right-to-left direction in FIG. 2; andthe Y-table as a table which is movable in the up-down direction, atable movable in the left-to-right or right-to-left direction in FIG. 2may also be defined as the Y-table; and a table movable in the up-downdirection as the X-table.

Loader

The loader 60 comprises a robot-type first carrier unit 61 disposedwithin the housing 22 of the mini-environment device 20; and arobot-type second carrier unit 63 disposed within the second loadingchamber 42.

The first carrier unit 61 comprises an articulated arm 612 rotatableabout an axis O₁-O₁ with respect to a driver 611. While an arbitrarystructure may be used for the articulated arm, the articulated arm inthis embodiment has three parts which are pivotably attached to eachother. One part of the arm 612 of the first carrier unit 61, i.e., thefirst part closest to the driver 611 is attached to a rotatable shaft613 by a driving mechanism (not shown in the diagram) of a knownstructure, disposed within the driver 611. The arm 612 is pivotableabout the axis O₁-O₁ by means of the shaft 613, and radially telescopicas a whole with respect to the axis O₁-O₁ through relative rotationsamong the parts. At a leading end of the third part of the arm 612furthest away from the shaft 613, a clamp 616 in a known structure forclamping a wafer, such as a mechanical chuck or an electrostatic chuck,is disposed. The driver 611 is movable in the vertical direction by anelevating mechanism 615 is of a known structure.

The first carrier unit 61 extends the arm 612 in either a direction MIor a direction M2 within two cassettes c held in the cassette holder 10,and removes a wafer accommodated in a cassette c by carrying the waferon the arm or by clamping the wafer with the chuck (not shown in thediagram) attached at the leading end of the arm. Subsequently, the armis retracted (in a state as illustrated in FIG. 2), and then rotated toa position at which the arm can extend in a direction M3 toward thepre-aligner 25, and stopped at this position. Then, the arm is extendedto transfer the wafer held on the arm to the pre-aligner 25. Afterreceiving a wafer from the pre-aligner 25, contrary to the foregoing,the arm is further rotated and stopped at a position at which it canextend to the second loading chamber 41 (in the direction M4), andtransfers the wafer to a wafer receiver 47 within the second loadingchamber 41. For mechanically clamping a wafer, the wafer should beclamped at a peripheral region (in a range of approximately 5 mm fromthe peripheral edge). This is because the wafer is formed with devices(circuit pattern) over the entire surface except for the peripheralregion, and clamping the inner region would result in failed ordefective devices.

The second carrier unit 63 is basically identical to the first carrierunit 61 in structure except that the second carrier unit 63 carries awafer between the wafer rack 47 and the carrying surface of the stagedevice 50, so that detailed description thereon is omitted.

In the loader 60, the first and second carrier units 61, 63 carry awafer from a cassette held in the cassette holder 10 to the stage device50 disposed in the working chamber 31 and vice versa, while keeping thewafer substantially in a horizontal state. The arms of the carrier unitsare moved in the vertical direction only when a wafer is removed fromand inserted into a cassette, when a wafer is carried on and removedfrom the wafer rack, and when a wafer is carried on and removed from thestage device 50. It is therefore possible to smoothly carry a wafer evenif it is a large one, for example, a wafer having a diameter of 30 cm.

Transfer of Wafer

Next, the transfer of a wafer in the apparatus will be described insequence from the cassette c held by the cassette holder 10 to the stagedevice 50 disposed in the working chamber 31.

As described above, when the cassette is manually set, the cassetteholder 10 having a structure adapted to the manual setting is used, andwhen the cassette is automatically set, the cassette holder 10 having astructure adapted to the automatic setting is used. In this embodiment,as the cassette c is set on the up/down table 11 of the cassette holder10, the up/down table 11 is moved down by the elevating mechanism 12 toalign the cassette c with the access port 225.

As the cassette is aligned with the access port 225, a cover (not shownin the diagram) provided for the cassette is opened, and a cylindricalcover is applied between the cassette c and the access port 225 of themini-environment to block the cassette and the mini-environment space 21from the outside. Since these structures are known, detailed descriptionof their structures and operations is omitted. When the minienvironmentdevice 20 is provided with a shutter for opening and closing the accessport 225, the shutter is operated to open the access port 225.

On the other hand, the arm 612 of the first carrier unit 61 remainsoriented in either the direction M1 or M2 (in the direction M2 in thisdescription). As the access port 225 is opened, the arm 612 extends toreceive one of the wafers accommodated in the cassette at the leadingend. While the arm and a wafer to be removed from the cassette areadjusted in the vertical position by moving up or down the driver 611and the arm 612 of the first carrier unit 61 in this embodiment, theadjustment may be made by moving the up/down table 11 of the cassetteholder 10, or made by both.

As the arm 612 receives the wafer, the arm 612 is retracted, and theshutter is operated to close the access port (when the shutter isprovided). Next, the arm 612 is pivoted about the axis O₁-O₁ such thatit can extend in the direction M3. Then, the arm 612 is extended andtransfers the wafer carried at the leading end or clamped by the chuckonto the pre-aligner 25 which aligns the orientation of the rotatingdirection of the wafer (the direction about the central axis vertical tothe wafer plane) within a predetermined range. Upon completion of thealignment, the carrier unit 61 retracts the arm 612 after a wafer hasbeen received from the prealigner 25 to the leading end of the arm 612,and rotates the arm 612 to a position in which the arm 612 can beextended in a direction M4. Then, the door 272 of the shutter device 27is moved to open the access ports 226, 436, and the arm 612 is extendedto place the wafer on the upper stage or the lower stage of the waferrack 47 within the first loading chamber 41. It should be noted thatbefore the shutter device 27 opens the access ports 226, 436 to transferthe wafer to the wafer rack 47, the opening 435 formed through thepartition wall 434 is closed by the door 461 of the shutter 46 in anair-tight state.

In the process of carrying a wafer by the first carrier unit, clean airflows (as downflow) in laminar flow from the gas supply unit 231disposed on the housing of the minienvironment device to prevent dustfrom attaching to the upper surface of the wafer while being carried. Aportion of the air near the carrier unit (in this embodiment, about 20%of the air supplied from the supply unit 231, which is substantiallycontaminated air) is sucked from the suction duct 241 of the discharger24 and discharged outside the housing. The remaining air is recoveredthrough the recovery duct 232 disposed on the bottom of the housing andreturned again to the gas supply unit 231.

As the wafer is placed into the wafer rack 47 within the first loadingchamber 41 of the loader housing 40 by the first carrier unit 61, theshutter device 27 is closed to seal the loading chamber 41. Then, thefirst loading chamber 41 is filled with an inert gas to expel air.Subsequently, the inert gas is also discharged so that a vacuumatmosphere dominates within the loading chamber 41. The vacuumatmosphere within the loading chamber 41 may be at a low vacuum degree.When a certain degree of vacuum is formed within the loading chamber 41,the shutter 46 is operated to open the access port 434 which has beensealed by the door 461, and the arm 632 of the second carrier unit 63 isextended to receive one wafer from the wafer receiver 47 with the clampat the leading end (the wafer is carried on the leading end or clampedby the chuck attached to the leading end). Upon completion of thereceipt of the wafer, the arm 632 is retracted, followed by the shutter46 again operated to close the access port 435 by the door 461. Itshould be noted that the arm 632 previously takes a posture in which itcan extend in the direction NI of the wafer rack 47 before the shutter46 is operated to open the access port 435. Also, as described above,the access ports 437, 325 are closed by the door 452 of the shutter 45before the shutter 46 is opened to block communication between thesecond loading chamber 42 and the working chamber 31 in an air-tightstate, so that the second loading chamber 42 can be evacuated.

As the shutter 46 is operated to close the access port 435, the secondloading chamber 42 is again evacuated at a higher degree of vacuum thanthe first loading chamber 41. Meanwhile, the arm 632 of the secondcarrier unit 63 is rotated to a position from which it can extend towardthe stage device 50 within the working chamber 31. On the other hand, inthe stage device 50 within the working chamber 31, the Y-table 52 ismoved upward, as viewed in FIG. 2, to a position at which the centerline X₀-X₀ of the X-table 53 substantially aligns with an X-axis X₁-X₁which passes a pivotal axis O₂-O₂ of the second carrier unit 63. TheX-table 53 in turn is moved to the position closest to the leftmostposition in FIG. 2, and remains at this position. When the secondloading chamber 42 is evacuated to substantially the same degree ofvacuum as the working chamber 31, the door 452 of the shutter 45 ismoved to open the access ports 437, 325, allowing the arm 632 to extendso that the leading end of the arm 632, which holds a wafer, approachesthe stage device 50 within the working chamber 31. Then, the wafer isplaced on the carrying surface 551 of the stage device 50. As the waferhas been placed on the carrying surface 551, the arm 632 is retracted,followed by the shutter 45 operated to close the access ports 437, 325.

The description above explained the operations in which a wafer in thecassette c is carried and placed on the stage device 50. For returning awafer, which has been carried on the stage device 50 and processed, fromthe stage device 50 to the cassette c, the operation reverse to theabove description is performed. Since a plurality of wafers are storedin the wafer rack 47, the first carrier unit 61 can carry a waferbetween the cassette and the wafer rack 47 while the second carrier unit63 can carry a wafer between the wafer rack 47 and the stage device 50,so that the inspecting operation can be efficiently carried out.

Specifically, when there is a wafer A, which has been already beenprocessed, and a wafer B, which has not yet been processed, in a waferrack 47 of a second carrier unit,

(1) first, the wafer B which has not yet been processed is transferredto the stage 50 and the processing is started;(2) during this processing, the wafer A which has already been processedis transferred from the stage 50 to the wafer rack 47 by an arm, a waferC which has not yet been processed is picked up from the wafer rackagain by the arm, which after having been positioned by a pre-aligner,is further transferred to the wafer rack 47 of a loading chamber 41.

This procedure may allow the wafer A, which has already been processed,to be substituted by the wafer C, which has not yet been processed, inthe wafer rack 47, during processing of wafer B.

Alternatively, depending on how such an apparatus executes an inspectionand/or an evaluation, a plurality of stage units 50 may be arranged inparallel, and in this case, wafers are transferred from one wafer rack47 for each of the stage units 50, thereby providing simultaneousprocessing of a plurality of wafers.

FIG. 6 illustrates typical modifications to the method of supporting themain housing 30. In a typical modification illustrated in FIG. 6, ahousing supporting device 33 a is made of a thick rectangular steelplate 331 a, and a housing body 32 a is carried on the steel plate.Therefore, the bottom wall 321 a of the housing body 32 a is thinnerthan the bottom wall 222 of the housing body 32 in the foregoingembodiment. In a typical modification illustrated in FIG. 7, a housingbody 32 b and a loader housing 40 b are suspended from a frame structure336 b of a housing supporting device 33 b. Lower ends of a plurality ofvertical frames 337 b fixed to the frame structure 336 b are fixed tofour corners of a bottom wall 321 b of the housing body 32 b, such thatthe peripheral wall and the top wall are supported by the bottom wall.Then, a vibration isolator 37 b is disposed between the frame structure336 b and a base frame 36 b. Likewise, the loader housing 40 b issuspended by a suspending member 49 b fixed to the frame structure 336.In the typical modification of the housing body 32 b illustrated in FIG.7, the housing body 32 b is supported in suspension, the center ofgravity of the main housing and a variety of devices disposed therein,as a whole, can be brought downward. The methods of supporting the mainhousing and the loader housing, including the typical modificationsdescribed above, are configured to prevent vibrations from beingtransmitted from the floor to the main housing and the loader housing.

In another typical modification, not shown in the diagram, only thehousing body of the main housing is supported by the housing supportingdevice from below, while the loader housing may be placed on the floorin the same way as the adjacent mini-environment device. Alternatively,in a further typical modification, not shown in the diagram, only thehousing body of the main housing is supported by suspension from theframe structure while the loader housing may be placed on the floor inthe same way as the adjacent mini-environment device.

According to the embodiment described above, the following advantagesare provided:

(A) the general configuration can be established for an inspectionapparatus in accordance with an electron beam based projection scheme,which can process objects under inspection at a high throughput;(B) a clean gas is forced to flow onto an object to be inspected withinthe mini-environment space to prevent dust from attaching to the objectto be inspected, and a sensor is provided for observing the cleanliness,thereby making it possible to inspect the object to be inspected whilemonitoring dust within the space;(C) when the loading chamber and the working chamber are integrallysupported through a vibration isolator, an object to be inspected can becarried to the stage device and inspected thereon without being affectedby the external environment.

Electron-Optical-System

The electron-optical system 70 comprises a column 71 fixed on thehousing body 32. Disposed within the column 71 are an optical systemcomprised of a primary light source optical system (hereinafter simplycalled the “primary optical system”) 72 and a secondary electron opticalsystem (hereinafter simply called the “secondary optical system”) 74,and a detecting system 76, as illustrated generally in FIG. 8. Theprimary optical system 72, which is an optical system for irradiatingthe surface of a wafer W to be inspected with an electron beam,comprises a light source 10000(beam generator) for emitting an electronbeam; and a mirror 10001 for changing the angle of the light beam. Inthis embodiment, the optical axis of a light beam 10000A emitted fromthe light source 10000 is oblique to the optical axis of irradiationalong which the wafer W to be inspected is irradiated with thephotoelectron beam (perpendicular to the surface of the wafer).

The detecting system 76 comprises a detector 761 and an image processingunit 763 which are disposed on a focal plane of the lens system 741.

Light Source (Light Beam Source) In the present embodiment a DUV laserbeam source is used in the light source 10000. The DUV laser beam isemitted from the DUV laser beam source 10000. Further, other beamsources (beam generator) may be used if a photoelectron is emitted froma substrate which is irradiated with a light from a light source 10000such as UV, DUV, EUV light and laser, and X ray and X ray laser etc.

Primary Optical System

A section for forming a light beam irradiated from the light source10000 and irradiating the light beam against a wafer W surface, whichforms a rectangle or circle (ellipse) on said wafer W surface, saidsection is called the primary optical system. The light beam irradiatedfrom the light source 10000 is irradiated as a primary light beam on awafer WF on the stage device 50 after passing through the lens opticalsystem 724.

Secondary Optical System

A two-dimensional secondary electron (photoelectron) image generated bya light beam or laser beam irradiated onto a wafer W is formed into animage by passing through a hole formed on the mirror 10001, passingthrough a numerical aperture 10008 by electrostatic lenses (TransferLenses) 10006 and 10009 formed on a location of field stop and magnifiedand projected by a subsequent stage of lens 741. Said image-forming andprojecting optical system is called the secondary optical system 74.

At that time, a negative bias voltage is applied to the wafer. Thephotoelectrons generated from the sample surface by the potentialdifference between the electrostatic lenses 724 (lens 724-1 and 724-2)are accelerated which effectively reduces chromatic aberration. Theextraction field in this lens optical system 724 is 3 kV/mm˜10 kV/mmwhich is a high electric field. The relationship where aberration iseffectively decreased and resolution is improved is caused by increasingthe extraction field. However, when the extraction field is increased,voltage gradient increases and discharge occurs easily. Therefore, it isimportant that the extraction field is used by selecting an appropriatevalue. Electrons which are magnified by a certain magnification by thelenses 724 (CL) are converged by the lens (TL1) 10006, and a cross over(CO) is formed on the numerical aperture 10008 (NA). In addition, it ispossible to zoom the magnification by a combination of lens (TL1) 10006and lens (TL2) 10009.

Following this, an image is magnified and projected by lens (PL) 741 inan MCP (Micro Channel Plate) in the detector 761. The present opticalsystem is formed by disposing an NA between TL1-TL2 and furtheroptimization of this optical system can reduce off-axis aberrations.

Detector

An electron image from the wafer, which is formed into an image by thesecondary optical system, is primarily amplified in the micro-channelplate (MCP) and then impinges against a fluorescent screen to beconverted into an optical image. As for the principle of the MCP,millions of very thin glass capillaries made of conductive material,each having a diameter of 6 to 25 μm and a length of 0.24 to 1.0 mm, arebundled and formed into a thin plate, and application of a specifiedvoltage makes each of the capillaries work as an individual electronamplifier so as to form the electron amplifier as a whole.

The image that has been converted into the light by said detector isprojected on the TDI (Time Delay Integration)-CCD (Charge CoupledDevice) by the FOP (Fiber Optical Plate) system disposed in theatmosphere through a vacuum permeable window on a one-to-one basis. Inaddition, as an alternative method, the FOP coated with a fluorescentmaterial connects with the surface of the TDI sensor and anelectron/light converted signal in the vacuum is introduced to the TDIsensor. This method has greater transmittance and MTF (ModulationTransfer function) efficiency than when places in an atmosphere. Forexample, a high value of ×5˜×10 can be obtained in transmittance andMTF. At this time, as described above, MCP+TDI is sometimes used as adetector. However, EB (Electron Bombardment)-TDI or EB-CCD may also beused instead. When EB-TDI is used, because photoelectrons generated formthe sample surface and which form a two dimensional image are directlyirradiated into the EB-TDI sensor surface, an image signal can be formedwithout deterioration in resolution. For example, when MCP+TDI is used,after electrons are amplified by the MCP they are converted to light bya fluorescent material or scintillator are this light image data isdelivered to the TDI sensor. In contrast to this, in an EB-TDI, EB-CDDsensor, a signal is delivered to the sensor without image deteriorationbecause there is no transmitted part or loss in electron lightconversion and light amplification data. For example, MTF or contrastbecomes ½˜⅓ when MCP+TDI is used compared to when EB-TDI or EB-CDD isused.

Furthermore, in the present embodiment, the lens system 724 is appliedwith a high voltage of 10 to 50 kV and a wafer W is disposed.

Description of the Relationship Among Main Functions in the ProjectingMethod and its General View

A schematic general view of an inspection device according to thepresent invention is shown in FIG. 9. However, some components areomitted for illustration.

In FIG. 9, the inspection device has a lens column 71, a light sourcecolumn 7000 and a chamber 32. A light source 10000 is arranged on theinside of the light source column 7000, and a primary optical system 72is disposed along the optical axis of a light beam (a primary lightbeam) irradiated from the light source 10000. Further, a stage 50 isinstalled in the interior of the chamber 32 and a wafer W is loaded onthe stage 50.

On the other hand, in the interior of the lens column 71, a cathode lens724 (724-1 and 724-2), transfer lenses 10006 and 10009, a numericalaperture (NA) 10008, a lens 741, and a detector 761 are located on theoptical axis of the secondary electron beam emanating from the wafer W.It is to be noted that the numerical aperture (NA) 10008 corresponds toan aperture diaphragm, which is a thin plate made of metal (Mo or thelike) having a circular aperture formed therein.

On the other hand, the output from the detector 761 is input into acontrol unit 780, and the output from the control unit 780 is input intoa CPU 781. A control signal from the CPU 781 is input into a lightsource control unit 71 a, a lens column control unit 71 b and a stagedriving mechanism 56. The light source control unit 71 a controls thepower supply of the light source 10000, and the lens column control unit71 b controls lens voltages in the cathode lens 724, the lenses 10006and 10009 and the lens 741 and also a voltage (amount of deviation) ofan aligner (not shown in the diagram).

Further, the stage driving mechanism 56 transmits position data of thestage to the CPU 781. Still further, the light source column 7000, lenscolumn 71, and the chamber 32 are connected to the vacuum exhaustingsystem (not shown in the diagram) and exhausted by a turbo pump in thevacuum exhausting system so as to maintain the interior thereof in avacuum. In addition, a roughing vacuum exhaust device system formed froma usual dry pump or rotary pump is disposed on the downstream of theturbo pump.

When the primary light beam is irradiated onto the sample,photoelectrons are generated as a secondary beam from the light beamirradiated surface of the wafer W.

The secondary beam is led to the detector via the TL lens group 10006and 10009 and the lens (PL) 741 thereby to form an image.

The cathode lens 724 is formed by three electrodes. Among thoseelectrodes, the one at the lowest position is designed to form apositive electric field between the potentials in the sample W side anditself, and to take in electrons (particularly, secondary electrons withsmaller directivities) so that the electrons may be efficientlyintroduced into the lens. As a result, the cathode lenses are effectivewhen they become telecentric. The secondary beam which forms an imagevia the cathode lens passed through a hole of the mirror 10001.

If the secondary beam is formed into an image only by one stage of thecathode lens 724, the lens effect may be great and an aberration is morelikely to occur. Accordingly, the cathode lens 724 may be combined witha second lens to perform first image forming. In this case, anintermediate image forming position is between the lens (TL1) 10006 andthe cathode lens 724. In addition, at this time, by making the lensestelecentric it is extremely effective for reducing aberration asdescribed above. The secondary beam is converged on the numericalaperture (NA) 10008 via the cathode lens 724 and lens (TL1), lens 10008and a cross over is formed. An image is first formed between the lens724 and lens (TL1) 10006, then an intermediate magnification isdetermined by the lens (TL1) 10006 and lens (TL2) 10009 and an image isformed on the detector 761 after magnification by the lens (PL). Inother words, an image is formed a total of 3 times in this example.

In addition, each of the lenses 10006, 10009, and lens 714 should be alens symmetrical with respect to a rotating axis of the kind referred toas a uni-potential lens or Einzell lens. Each lens is composed of threeelectrodes, in which typically the outer two electrodes have zeropotentials and a voltage applied to the center electrode is used tocause a controlling lens effect. Further, not limited to this lensstructure, a structure having a focus adjustment electrode on the firststage, second stage or both stages of the lens 724, or a fourth or fifthdynamic focus adjustment electrode may be disposed. Also, a field lensfunction may be added to the PL lens 741 and it is effective to add afourth or fifth electrode for reducing off-axis aberrations andincreased magnification.

The secondary beam is magnified and projected by the secondary opticalsystem and formed into an image on the detection plane of the detector761. The detector 761 comprises a MCP for amplifying an electron, afluorescent screen for converting the electrons into light, lenses andother optical elements for use as a relay and transmitting an opticalimage between the vacuum system and external components, and an imagesensor (CCD or the like). The secondary beam is formed into an image onthe MCP detection plane and amplified, and then the electrons areconverted into light signals by the fluorescent screen, which are inturn converted into photo-electric signals by the image sensor.

The control unit 780 reads out the image signal of the wafer W from thedetector 761 and transmits it to the CPU 781. The CPU 781 performs adefect inspection of the pattern by template matching and so forth fromthe image signal. In addition, the stage 50 is adapted to be movable inthe X and Y directions by a stage driving mechanism 56. The CPU 781reads the position of the stage 50 and outputs a drive control signal tothe stage driving mechanism 56 to drive the stage 50, allowing forsequential detection and inspection of the images.

In addition, even if the setting magnification of the lens conditions oflens 10006 and 10009 are changed, a uniform image over the field of viewcan be obtained in the detection side. Further, although an even anduniform image can be obtained in the present embodiment, typically,increasing the magnification may problematically cause deterioration inthe brightness of the image. Accordingly, in order to improve thisproblematic condition, when the lens condition for the secondary opticalsystem is changed to vary the magnification factor, the lens conditionfor the primary optical system should be set such that the amount ofelectrons discharged per unit pixel be constant.

Precharge Unit

The precharge unit 81, as illustrated in FIG. 1, is disposed adjacent tothe lens column 71 of the electron-optical system 70 within the workingchamber 31. Since this inspection apparatus is configured to inspectdevice patterns or the like formed on the surface of a substrate orwafer to be inspected by irradiating the wafer with an electron beam, sothat the photoelectrons generated by the irradiation of the light beamare used as information on the surface of the wafer. However, thesurface of the wafer may be charged up depending on conditions such asthe wafer material, the wavelength or energy of the irradiated light orlaser beam, and so on. Further, on the surface of a wafer, some regionsmay be highly charged, while other regions may be lightly charged.Variations in the amount of charge on the surface of the wafer causecorresponding variations in information provided by the resultingphotoelectrons, thereby failing to provide correct information. Forpreventing such variations, in this embodiment, the precharge unit 81 isprovided with a charged particle irradiating unit 811. Before electronsfor inspection are irradiated to a predetermined region on a wafer to beinspected, charged particles are irradiated from the charged particleirradiating unit 811 of the precharge unit 81 to eliminate variations incharge. The charges on the surface of the wafer may be detected bypreviously forming an image of the surface of the wafer to be inspected,and by evaluating the image, and the precharge unit 81 can be operatedbased on such detection.

FIG. 10 shows the main components of a precharge unit of an embodimentaccording to the present invention.

Charged particles 818 from a charged particle irradiation source 819 areaccelerated with a voltage determined by a bias supply 820 so as to beirradiated onto a wafer W. An inspecting region 815, and a region 816 aswell, are indicated as locations that have been already exposed to thecharged particle irradiation for a pre-treatment, and the region 817 isindicated as a location which is currently exposed to the chargedparticle irradiation. In the diagram, although the sample substrate W isshown to be scanned in the direction indicated with an arrow, anothercharged particle beam source 819 may be arranged on the opposite side tothe first electron beam source as shown with the dotted line in thedrawing, so that the charged particle beam sources 819 and 819 may bealternately turned on and off in synchrony with the direction of thescanning of the sample W. In this case, if the energy of the chargedparticles is too high, the secondary electron yield from an insulatingportion of the sample substrate W would exceed 1, thus causing thesurface to be positively charged, and even a yield of not more than 1would still make the phenomenon complicated with the generated secondaryelectrons thus decreasing the irradiation effect, and accordingly, it ispreferred that the voltage for the energy of the charged particlesshould be set to a landing voltage of 100 eV or lower (preferably higherthan 0 eV and lower than 30 eV), which can significantly reduce thegeneration of the secondary electrons.

FIG. 11 shows a second embodiment of a precharge unit of the presentinvention. FIG. 11 shows an irradiation source of such type thatirradiates an electron beam as a charged particle beam. The irradiationsource comprises a hot filament 821, a deriving electrode 824, a shieldcase 826, a filament power supply 827, and an electron deriving powersupply 823. The deriving electrode 824 is 0.1 mm in thickness, has aslit 0.2 mm wide and 1.0 mm long, and is arranged relative to thefilament 821 of a diameter of 0.1 mm so as to take the form of a threeelectrode type electron gun. The shield case 826 is also provided with aslit of 1 mm wide and 2 mm long, and is assembled so that the shieldcase 826 is spaced from the deriving electrode 824 by 1 mm with its slitcenter being aligned with the slit center of the deriving electrode 824.The filament is made of tungsten (W), and it is found that an electroncurrent of in the order of μA can be obtained with a current of 2 Abeing supplied to the filament when a deriving voltage of 20 V and abias voltage of −30 V are applied.

The example has been shown for illustrative purposes only and thefilament may be made of other materials, for example, a high meltingpoint metal such as Ta, Ir, Re or the like, thoria-coated W, or an oxideelectrode, and in this case, needless to say, the filament currentshould be varied depending on the material, the line diameter and theline length to be used. Further, other kinds of electron guns may beused as long as the electron beam irradiated area, the electron currentand the energy can be respectively set to appropriate value.

FIG. 12 shows a third embodiment of a precharge unit of the presentinvention. FIG. 12 shows an irradiation source of a type that irradiatesions 829 as a charged particle beam. This irradiation source comprises afilament 821, a filament power supply 822, an electric discharge powersupply 827, and an anode shield case 826, in which both of anode 828 andthe shield case 826 have the same sized slit of 1 mm×2 mm respectivelyformed there through, and they are assembled so that the centers of bothslits are aligned with each other. Ar gas 830 is introduced into theshield case 826 through a pipe 831 with about 1 Pa and this irradiationsource is operated by way of an arc discharge caused by the hot filament821. The bias voltage is set to a positive value.

FIG. 13 shows a plasma irradiation type of a fourth embodiment of aprecharge unit according to the present invention. It has the samestructure as that of FIG. 20. The operation thereof, similarly to theabove description, is made effective by way of the arc discharge by thehot filament 821, in which by setting the bias potential to 0V, theplasmas 832 are forced by gas pressure to effuse through the slit to beirradiated onto a sample substrate. Since in the plasma irradiationmethod, the beam is composed of a group of particles that has bothpositive and negative charges, which is different from the otherirradiation methods, it allows both positive and negative surfacepotentials in the surface of the sample substrate to approach zero.

A charged particle irradiating section 819 arranged in the proximity ofthe wafer W has a configuration as illustrated in any of FIGS. 10 to 13,which is designed to irradiate charged particles 818 onto the samplesubstrate with a suitable condition depending on the difference in thesurface structure, e.g., silicon dioxide film or silicon nitride film,of the wafer W, or depending on a different requirement for each samplesubstrate after respective different processes, and in which afterperforming the irradiation to the sample substrate under the optimalirradiation condition, that is, after smoothing the potential in thesurface of the wafer W or saturating the potential therein with thecharged particles, an image is formed by the irradiated light, or laseror electron beam 711 and secondary charged particles 712 to be used todetect any defects.

As described above, since according to the subject embodiment,pre-treatment by means of charged particle irradiation is employed justbefore measurement and thereby an evaluated image distortion by thecharging would not occur or would be negligible, any defects can beaccurately detected.

Further, according to the embodiment according to the present invention,since a large amount of an irradiated light, laser or primary electronbeam is irradiated for scanning a stage has caused problems in the priorart, a large number of secondary electrons of an electron beam,secondary emitted electrons or mirror electrons can be detected and adetection signal having a good S/N ratio can be obtained, thus improvingthe reliability of defect detection.

Still further, with a larger S/N ratio, faster scanning of the stagestill can produce good image data, thus allowing inspection throughputto be greater.

Potential Applying Mechanism

Referring next to FIG. 14, the potential applying mechanism 83 applies apotential of ±several volts to a carrier of a stage, on which the waferis placed, to control the generation of secondary electrons based on thefact that the generation rate of secondary electron charged particlesemitted from the wafer or secondary system transmittance rate depend onthe potential on the wafer. In addition, in the case of irradiating anelectron beam in the primary system, the potential applying mechanism 83also serves to decelerate the energy originally possessed by irradiatedelectrons to provide the wafer with irradiated electron energy ofapproximately 0 to 500 eV. In addition, the energy of the electronswhich move through the secondary system is determined by forming areference voltage of the wafer which is the sample.

As illustrated in FIG. 14, the potential applying mechanism 83 comprisesa voltage applying device 831 electrically connected to the carryingsurface 541 of the stage device 50; and a charging examining/voltagedetermining system (hereinafter referred to as examining/determiningsystem) 832. The examining/determining system 832 comprises a monitor833 electrically connected to an image forming unit 763 of the detectingsystem 76 in the electron-optical system 70; an operator 834 connectedto the monitor 833; and a CPU 835 connected to the operator 834. The CPU835 supplies a signal to the voltage applying device 831.

The potential applying mechanism 83 is designed to find a potential atwhich the wafer to be inspected is hardly charged, and to apply suchpotential to the carrying surface 541.

In a method for inspecting an electrical defect on a sample to beinspected, the defect on the portion which is designed to beelectrically insulated can be detected based on the fact that there is avoltage difference therein between the normal case where the portion isinsulated and the defective case where the portion is in a conductivecondition.

In this method, at first the electric charges are applied to the samplein advance, so that a voltage difference is generated between thevoltage in the portion essentially insulated electrically and thevoltage in another portion which is designed to be electricallyinsulated but is in a conductive condition due to the existence of anydefects, then the beam of the present invention is applied thereto toobtain data about the voltage difference, which is then analyzed todetect the conductive condition.

Irradiation Beam Calibration Mechanism

Referring next to FIG. 15, the irradiation beam calibration mechanism 85comprises a plurality of Faraday cups 851, 852 for measuring a beamcurrent, disposed at a plurality of positions in a lateral region of thewafer carrying surface 541 on the turntable 54, and a reference sample853. A material including a matrix pattern formed with a part of a planesurface without a pattern and a matrix pattern reference pitch can beused as the reference sample 853. A conductive material is used for theplane surface. When light or a laser is irradiated on these parts, inorder to be able to measure the irradiated region of the beam anelectron image generated from the part irradiated at a low magnificationis imaged and calculated by its gray profile. A stable measurement canbe made because the surface potential is stable when conductive. Inaddition, it is possible to measure the size of an irradiated part fromthe profile of an electron image of the irradiated part and the size ofan irradiated part and intensity profile from the pitch relationship atfor example, a pitch of 2 μm because the pitch can be obtained whenthere is a matrix pattern. In addition, it is also possible use Faradaycups. When Faraday cups are used, light or a laser is irradiated intoparts having holes, and an electron image of the obtained irradiatedregion is obtained. Then, it is possible to measure the size andcoordinates of the irradiated region by comparing the size of the holesof the Faraday cups and the irradiated region. Also, it is possible touse original Faraday cups when an electron beam is used as theirradiation beam. When an electron beam is irradiated into the Faradaycup, it is possible to measure the current of the electron beam. TheFaraday cups 851 are provided for a narrow beam (approximately (φ2 μm),while the Faraday cuts 852 for a wide beam (approximately (φ30 μm). TheFaraday cups 851 are provided for a narrow beam measure a beam profileby driving the turntable 54 step by step, while the Faraday cups 852 fora wide beam measure a total amount of current. The Faraday cups 851, 852are mounted on the wafer carrying surface 541 such that their topsurfaces are coplanar with the upper surface of the wafer W carried onthe carrying surface 541. In this way, the primary electron beam emittedfrom the electron gun is monitored at all times. This is because theelectron gun cannot emit a constant electron beam at all times butvaries in its emission intensity as it is used over a period of time.

Alignment Controller

The alignment controller 87 aligns the wafer W with the electron-opticaldevice 70 using the stage device 50, and it performs the control forrough alignment through wide view field observation using the opticalmicroscope 871 (a measurement with a lower magnification than themeasurement made by the electron-optical system); high magnificationalignment using the electron-optical system of the electron-opticaldevice 70; focus adjustment; inspecting region setting; patternalignment; and so on. The reason why the wafer is inspected at a lowmagnification using the optical microscope in this way is that analignment mark must be readily detected by a photoelectron image whenthe wafer is aligned by observing patterns on the wafer in a small fieldusing the light or laser beam irradiation for automatically inspectingpatterns on the wafer. At this time, an electron beam can be usedinstead of a photoelectron for the irradiation beam.

The optical microscope 871 is disposed on the housing 30 (alternatively,it may be movably disposed within the housing 30), with a light source,not shown in the diagram, being additionally disposed within the housing30 for operating the optical microscope. The electron-optical system forobserving the wafer at a high magnification shares the electron opticalsystems (primary optical system 72 and secondary optical system 74) ofthe electron-optical device 70. The configuration may be generallyillustrated in FIG. 16. For observing a point of interest on a wafer ata low magnification, the X-stage 53 of the stage device 50 is moved inthe X-direction to move the point of interest on the wafer into a fieldof the optical microscope 871. The wafer is viewed in a wide field bythe optical microscope 871, and the point of interest on the wafer to beobserved is displayed on a monitor 873 through a CCD 872 to roughlydetermine a position to be observed. In this occurrence, themagnification of the optical microscope may be changed from a low to ahigh magnification.

Next, the stage system 50 is moved by a distance corresponding to aspacing ox between the optical axis O₃-O₃ of the electron-optical system70 and the optical axis O₄-O₄ of the optical microscope 871 to move thepoint on the wafer under observation, previously determined by theoptical microscope 871, to a point in the field of the electron-opticalsystem 70. In this occurrence, since the distance δx between the axisO₃-O₃ of the electron-optical system and the axis O₄-O₄ of the opticalmicroscope 871 is previously known (while it is assumed that theelectron optical system 70 is deviated from the optical microscope 871in the direction along the X-axis in this embodiment, it may be deviatedin the Y-axis direction as well as in the X-axis direction), the pointunder observation can be moved to the viewing position by moving thestage system 50 by the distance δx. After the point under observationhas been moved to the viewing position of the electron-optical system70, the point under observation is imaged by the electron optical systemat a high magnification for storing a resulting image or displaying theimage on the monitor 765 through the detector 761. At this time, lightor a laser beam is irradiated as the primary system and it is possibleto use as a photoelectron image. In addition, when an electron beam isused as the primary system, secondary emitting electrons or an electronimage is obtained and can be used in alignment.

After the point under observation on the wafer imaged by theelectron-optical system at a high magnification is displayed on themonitor 765, misalignment of the wafer in its rotating direction withrespect to the center of rotation of the turntable 54 of the stagesystem 50, and misalignment δθ of the wafer in its rotating directionwith respect to the optical axis O₃-O₃ of the electron-optical systemare detected by a known method; misalignment of a predetermined patternwith respect to the electron-optical system in the X-axis and Y-axis isalso detected. Then, the operation of the stage system 50 is controlledto align the wafer based on the detected values and data on aninspection mark attached on the wafer or data on the shape of thepatterns on the wafer which have been obtained in separation.

Vacuum Exhausting System

A vacuum exhausting system is comprised of a vacuum pump, a vacuumvalve, a vacuum gauge, a vacuum pipe and the like, and exhausts tovacuum an electron-optical system, a detector section, a sample chamber,a load-lock chamber and the like according to a predetermined sequence.In each of those sections, the vacuum valve is controlled so as toaccomplish a required vacuum level. The vacuum level is regularlymonitored, and in the case of irregularity, an interlock mechanismexecutes an emergency control of an isolation valve or the like tosecure the vacuum level. As for the vacuum pump, a turbo molecular pumpmay be used for the main exhaust.

A dry pump of Roots type may be used as a roughing vacuum pump. Apressure at an inspection spot (an electron beam irradiating section) ispractically in a range of 10⁻³ to 10⁻⁶ Pa, but more preferably, in arange of 10⁻⁴ to 10⁻⁶ Pa.

Control System

A control system is mainly comprised of a main controller, a controllingcontroller, and a stage controller.

The main controller is equipped with a man-machine interface, throughwhich an operator manipulates the controller (a variety ofinstructions/commands, an entry of recipe, an instruction to start aninspection, a switching between an automatic inspection mode and amanual inspection mode, an input of all of the commands required in themanual inspection mode and so forth). In addition, the main controllermay further execute communication with a host computer of a factory, acontrol of a vacuum exhausting system, a control of a carrying andpositioning operations of a sample such as a wafer, an operation forsending commands and receiving information to/from the other controllersand/or stage controller and so forth. Further, the main controller hasthe following functions: to obtain an image signal from an opticalmicroscope; a stage vibration compensating function for compensating adeterioration in the image by feeding back a fluctuation signal of thestage to an electronic-optical system; and an automatic focal pointcompensating function for detecting a displacement of the sampleobservation point in the Z direction (in the axial direction of thesecondary optical system) and feeding back the detected displacement tothe electron-optical system so as to automatically compensate the focalpoint. Sending and receiving operations of the feedback signal to andfrom the electron-optical system and sending and receiving operations ofthe signal to and from the stage are performed via the controllingcontroller and the stage controller respectively.

The controlling controller is mainly responsible for the control of theprimary optical system and the secondary electron optical system (alight source, a laser beam source, a mirror, an optical system lens, anelectron optical system lens, an aligner, a control of a high-precisionpower supply for a Wien filter or the like). Specifically, thecontrolling controller performs a control operation, for example, anautomatic voltage setting for each of the lens systems and the alignersin response to each operation mode (gang control), so that a constantelectron current may be regularly irradiated against the irradiationregion even if the magnification is changed, and a voltage to be appliedto each of the lens systems and the aligners may be automatically set inresponse to each magnification. In addition, when the magnificationchanges, it is effective to preform control in order to change thedensity of the irradiation beam so that the electron number per Px(electron number/Px Px: Pixel) obtained by the detector is maintainedconstant. It is possible to obtain an electron image with a differentmagnification at a constant level of luminosity.

The stage controller is mainly responsible for a control regarding tothe movement of the stage so that a precise movement in the X and the Ydirections may be performed in the order of μm (with tolerance of about±0.05 μm). Further, in the present stage, a control in the rotationaldirection (θ control) is also performed with a tolerance equal to orless than about ±0.1 seconds.

Cleaning of an Electrode

When an electron beam apparatus according to the present invention isoperated, a target substance floats due to a proximity interaction(charging of particles in the proximity of a surface) and is attractedto a high-voltage region, an organic substance will be deposited on avariety of electrodes used for forming or deflecting an electron beam.Since the insulating material gradually being deposited on the surfaceof the electrodes by the electric charge adversely affects the formingor deflecting mechanism for the electron beam, accordingly, thisdeposited insulating material must be periodically removed. To removethe insulating material periodically, an electrode adjacent to theregion where the insulating material has been deposited is used toproduce plasma of hydrogen, oxygen, fluorine, composition includingthese elements, HF, O₂, H₂O, C_(M)F_(N) or the like, to maintain theplasma potential in the space to the degree (several kV, e.g. 20 V˜5 kV)so that sputtering is caused on the electrode surface, thereby allowingonly the organic substance to be removed by oxidization, hydrogenationor fluorination.

Modified Embodiment of the Stage Device

FIG. 17 shows a modified embodiment of a stage device in the detectoraccording to the present invention. A division plate 914 is attachedonto an upper face of a Y directionally movable unit 95 of a stage 93,wherein said division plate 914 overhangs to a considerable degree,approximately horizontally in the +Y direction and the −Y direction (thelateral direction in FIG. 17 (B)), so that between an upper face of an Xdirectionally movable unit 96 and said division plate 914 there isalways provided a narrow gap 950. Also, a similar division plate 912 isattached onto the upper face of the X directionally movable unit 96 soas to overhang in the ±X direction (the lateral direction in FIG.17(A)), so that a narrow gap 951 may be constantly formed between anupper face of a stage table 97 and said division plate 912. The stagetable 97 is fixedly secured onto a bottom wall within a housing 98 usinga known method.

In this way, since the narrow gaps 950 and 951 are constantly formedwherever the sample table 94 may move, and the gaps 950 and 951 canprevent the movement of a desorbed gas even if a gas is desorbed orleaked along the guiding plane 96 a or 97 a upon movement of the movableunit 95 or 96, any increase in pressure can be considerably reduced in aspace 924 adjacent to the sample against which the charged particlesbeam is irradiated.

In a side-face and an under face of the movable unit 95 and also in anunder face of the movable unit 96 of the stage 93, there are providedgrooves, for differential exhausting formed surrounding hydrostaticbearings 90, as shown in FIG. 18, and which work for vacuum-exhausting;therefore, in a case where narrow gaps 950 and 951 have been formed, thedesorbed gas from the guiding planes is mainly evacuated by thesedifferential exhausting sections. Because of this, the pressures inspaces 913 and 915 within the stage are kept at higher levels than thepressure within chamber C. Accordingly, if there are more portionsprovided for vacuum-exhausting the spaces 913 and 915, in addition tothe differential exhausting grooves 917 and 918, the pressure within thespaces 913 and 915 can be decreased, and the pressure rise of the space924 in the vicinity of the sample can be controlled so as to be keptlower. For this purpose, vacuum exhausting channels 91-1 and 91-2 areprovided. The vacuum exhausting channel 91-1 extends through the stagetable 97 and the housing 98 to communicate with an outside of thehousing 98. On the other hand, the exhausting channel 91-2 is formed inthe X directionally movable unit 96 and opens in an under face thereof.

It is to be noted that though arranging the division plates 912 and 914might cause a problem requiring the chamber C to be extended so that itdoes not interfere with the division plates, this can be improved byemploying division plates of stretchable material or structure. Oneembodiment in this regard may be suggested, which employs the divisionplates made of rubber or in a form of bellows, the ends portions ofwhich are fixedly secured respectively in the direction of movement sothat each end of the division plate 914 is secured to the Xdirectionally movable unit 96 and that of the division plate 912 to theinner wall of the housing 98.

FIG. 19 shows a second modified embodiment of a stage device.

In this embodiment, a cylindrical divider 916 is disposed surroundingthe tip portion of the lens column or the charged particles beamirradiating section 72 so that a narrow gap may be produced between anupper face of a sample W and the tip portion of the lens column. In suchconfiguration, even if the gas is desorbed from the XY stage, andincreases the pressure within the chamber C, since a space 924 withinthe divider has been isolated by the divider 916 and exhausted with avacuum pipe 710, there could be generated a pressure difference betweenthe pressure in the chamber C and that in the space 924 within thedivider, thus controlling the pressure rise in the space 924 within thedivider 916 so that it is kept low. Preferably, the gap between thedivider 916 and the sample surface should be approximately some ten μmto several mm, depending on the pressure level to be maintained withinthe chamber C and in the surrounding of the irradiating section 72. Itis to be understood that the interior of the divider 916 is made tocommunicate with the vacuum pipe by the known method.

On the other hand, the charged particles beam irradiation apparatus maysometimes apply a high voltage of a few kV to the sample W, and so it isfeared that any conductive materials adjacent to the sample could causean electric discharge. In this case, the divider 916 made of insulatingmaterial such as ceramic or the surface of an insulating material suchas a polyimide coat (10˜50 μm) may be used in order to prevent anydischarge between the sample W and the divider 916.

It is to be noted that a ring member 94-1 arranged so as to surround thesample W (a wafer) is a plate-like adjusting part fixedly mounted on thesample table 94 and set to have the same height as the wafer so that amicro gap 952 may be formed throughout a full circle of the tip portionof the divider 916 even when the charged particles beam is beingirradiated against an edge portion of the sample such as the wafer.Thereby, whichever location on the sample W may be irradiated by thecharged particles beam, the constant micro gap 952 can always be formedat the tip portion of the divider 916 so as to maintain a stablepressure in the space 924 surrounding the lens column tip portion.

FIG. 20 shows another modified embodiment.

A divider 919 having a differential exhausting structure integratedtherein is arranged so as to surround the charged particles beamirradiating section 72 of a lens column 71. The divider 919 iscylindrical in shape and has a circular channel 920 formed insidethereof and an exhausting path 921 extending upwardly from said circularchannel 920. Said exhausting path 921 is connected to a vacuum pipe 923via an inner space 922. A micro space as narrow as some ten μm toseveral mm is formed between the lower end of the divider 919 and theupper face of the sample W.

With such configuration, even if the gas is discharged from the stage inassociation with the movement of the stage resulting in an increase ofthe pressure within the chamber C, and eventually flows into the spaceof tip portion or the charged particles beam irradiating section 72, anyflow of gas is blocked by the divider 919, which has reduced the gapbetween the sample W and itself so as to make the conductance very low,thus reducing the flow rate. Further, since any gas that has entered canbe exhausted through the circular channel 920 to the vacuum pipe 923,there will be almost no gas remained to flow into the space 924surrounding the charged particles beam irradiating section 72;accordingly, the pressure of the space surrounding the charged particlesbeam irradiating section 72 can be maintained at the desired high vacuumlevel.

FIG. 21 shows yet another modified embodiment.

A divider 926 is arranged so as to surround the charged particles beamirradiating section 72 in the chamber C, thus isolating the chargedparticles beam irradiating section 72 from the chamber C. This divider926 is coupled to a refrigerating machine 930 via a support member 929made of material of high thermal conductivity such as copper oraluminum, and is kept as cool as −100° C. to −200° C. A member 927 isprovided for blocking a thermal conduction between the cooled divider926 and the lens column and is made of material of low thermalconductivity such as ceramic, resin or the like. Further, a member 928is made of a non-insulating material such as ceramic or the like and isattached to the lower end of the divider 926 so as to prevent anyelectric discharge between the sample W and the divider 926.

With such configuration, any gas molecules attempting to flow into thespace surrounding the charged particles beam irradiating section fromthe chamber C are blocked by the divider 926, and even if some moleculesmanage to flow into the section, they are frozen to be captured on thesurface of the divider 926, thus allowing the pressure in the space 924surrounding the charged particles beam irradiating section to be keptlow. In this way, vacuum exhausting using a freezing gas repair deviceor a cryopanel is extremely effective for local exhausting.

Furthermore, various types of refrigerating machines may be used for therefrigerating machine in this embodiment, for example, a cooling machineusing liquid nitrogen, a He refrigerating machine, a pulse-tube typerefrigerating machine or the like.

FIG. 22 shows yet another modified embodiment.

The division plates 912 and 914 are arranged on both movable units ofthe stage 93 similarly to those illustrated in FIG. 17, and thereby, ifthe sample table 94 is moved to any location, the space 913 within thestage is separated from the inner space of the chamber C by thosedivision plates through the narrow gaps 950 and 951. Further, anotherdivider 916 similar to that as illustrated in FIG. 19 is formedsurrounding the charged particles beam irradiating section 72 so as toseparate a space 924 accommodating the charged particles beamirradiating section 72 therein from the interior of the chamber C with anarrow gap 952 disposed therebetween. Owing to this, upon movement ofthe stage, even if the gas adsorbed on the stage is desorbed into thespace 913 to increase the pressure in this space, the pressure increasein the chamber C is controlled so that it is kept low, and the pressureincrease in the space 924 is also kept even lower. This allows thepressure in the space 924 for irradiating the charged particles beam tobe maintained at a low level. Alternatively, employing the divider 919having the differential exhausting mechanism integrated therein asexplained with reference to the divider 916, (see FIG. 20), or thedivider 926 cooled with the refrigerating machine as shown in FIG. 21allows the space 924 to be maintained stably with further loweredpressure.

According to the subject embodiment, the following effects may beobtained.

(A) The stage device can enhance accurate positioning within a vacuumatmosphere and the pressure in the space surrounding the chargedparticles beam irradiating location is hardly increased. That is, itallows the charged particles beam processing to be applied to the samplewith high accuracy.(B) It is almost impossible for the gas desorbed or leaked from thehydrostatic bearing to go through the divider and reach the space forthe charged particles beam irradiating system. Thereby, the vacuum levelin the space surrounding the charged particles beam irradiating locationcan be further stabilized.(C) It is harder for the desorbed gas to go through to the space for thecharged particles beam irradiating system, and it is easier to maintainthe stability of the vacuum level in the space surrounding the chargedparticles beam irradiating location.(D) The interior of the vacuum chamber is partitioned into threechambers, i.e., a charged particles beam irradiation chamber, ahydrostatic bearing chamber and an intermediate chamber; each cancommunicate with the other via a small conductance. Further, the vacuumexhausting system is constructed so that the pressures in the respectivechambers are controlled sequentially, so that the pressure in thecharged particles beam irradiation chamber is the lowest, that in theintermediate chamber is in the middle range, and that in the hydrostaticbearing chamber is the highest. The pressure fluctuation in theintermediate chamber can be reduced by the divider, and the pressurefluctuation in the charged particles beam irradiation chamber can befurther reduced by another step of divider, so that the pressurefluctuation therein can be reduced substantially to a non-problematiclevel.(E) The pressure increase upon movement of the stage can be controlledso that it is kept low.(F) The pressure increase upon movement of the stage can be furthercontrolled so that it is kept even lower(G) Since a defect inspection apparatus with highly accurate stagepositioning performance and with a stable vacuum level in the chargedparticles beam irradiating region can be accomplished, an inspectionapparatus with high inspection performance and without any fear ofcontamination of the sample can be provided.(H) Since a defect inspection apparatus with highly accurate stagepositioning performance and with a stable vacuum level in the chargedparticles beam irradiating region can be accomplished, an exposingapparatus with high exposing accuracy and without any fear ofcontamination of the sample can be provided.(I) Manufacturing the semiconductor by using the apparatus with highlyaccurate stage positioning performance and with a stable vacuum level inthe charged particles beam irradiating region allows a miniaturizedmicro semiconductor circuit to be formed.

Furthermore, it is apparent that the stage device shown in FIGS. 17˜22can be applied to the stage device 50 shown in FIG. 1.

Further embodiments of the XY stage according to the present inventionwill now be described with reference to FIGS. 23 to 25. It is also to beappreciated that a term “vacuum” used in this specification means avacuum as referred to in the field pertaining to this art and does notnecessarily refer to an absolute vacuum.

FIG. 23 shows another embodiment of the XY stage.

A tip portion of a lens column 71 or a charged particles beamirradiating section 72, which functions to irradiate a charged particlesbeam against a sample, is mounted on a housing 98 defining a vacuumchamber C. The sample W loaded on a table of an XY stage 93 movable inthe X direction (the lateral direction in FIG. 23) is adapted to bepositioned immediately under the lens column 71. The XY stage 93 of highprecision allows the charged particles beam to be irradiated onto thissample W accurately in any arbitrary location of the sample surface.

A pedestal 906 of the XY stage 93 is fixedly mounted on a bottom wall ofthe housing 98, and a Y table 95 movable in the Y direction (thevertical direction on paper in FIG. 23) is loaded on the pedestal 906.Bump portions are formed on both opposite sidewall faces (the left andthe right side faces in FIG. 23) of the Y table 95 respectively, each ofwhich projects into a hollow groove formed on a side surface facing theY table in either of a pair of Y-directional guides 907 a and 907 bmounted on the pedestal 906. The hollow groove extends alongapproximately the full length of the Y directional guide in the Ydirection. A top, a bottom and a side face of respective bump portionsprotruding into the grooves are provided with known hydrostatic bearings911 a, 909 a, 911 b and 909 b respectively, through which ahigh-pressure gas is expelled and thereby the Y table 95 is supported tothe Y directional guides 907 a and 907 b in non-contact manner so as tobe movable smoothly reciprocating in the Y direction. Further, a linearmotor 932 of known structure is arranged between the pedestal 906 andthe Y table 95 for driving the Y table 95 in the Y direction. The Ytable 95 is supplied with the high pressure gas through a flexible pipe934 for supplying a high-pressure gas, and the high-pressure gas isfurther supplied to the above-described hydrostatic bearings 909 a to911 a and 909 b to 911 b though a gas passage (not shown in the diagram)formed within the Y table. The high-pressure gas supplied to thehydrostatic bearings is expelled into a gap of from several microns toseveral tens of microns in thickness formed respectively between thebearings and the opposing guide planes of the Y directional guide so asto position the Y table accurately with respect to the guide planes inthe X and Z directions (up and down directions in FIG. 23).

The X table 96 is loaded on the Y table so as to be movable in the Xdirection (the lateral direction in FIG. 23). A pair of X directionalguides 908 a and 908 b (only 908 a is illustrated in the diagram) withthe same configuration as of the Y directional guides 907 a and 907 b isarranged on the Y table 95 with the X table 96 sandwiched therebetween.Hollow grooves are also formed in the X directional guides on the sidesfacing the X table and bump portions are formed on the side portions ofthe X table (side portions facing the X directional guides). The hollowgroove extends approximately along the full length of the X directionalguide. A top, a bottom and a side face of respective bump portions ofthe X table protruding into the hollow grooves are provided withhydrostatic bearings (not shown in the diagram) similar to thosehydrostatic bearings 911 a, 909 a, 910 a, 911 b, 909 b and 910 b in thesimilar arrangements. A linear motor 933 of known configuration isdisposed between the Y table 95 and the X table 96 so as to drive the Xtable in the X direction. Further, the X table 96 is supplied with ahigh-pressure gas through a flexible pipe 931, and thus thehigh-pressure gas is supplied to the hydrostatic bearings. The X table96 is supported highly precisely with respect to the Y directional guidein a non-contact manner by way of said high-pressure gas blowing outfrom the hydrostatic bearings to the guide planes of the X-directionalguides. The vacuum chamber C is exhausted through vacuum pipes 919, 920a and 920 b coupled to a vacuum pump of a known structure. Those pipes920 a and 920 b penetrate the pedestal 906 at the top surface thereof toopen their inlet sides (inner side of the vacuum chamber) in theproximity of the locations to which the high-pressure gas is ejectedfrom the XY stage 93, so that the pressure in the vacuum chamber may beprevented to the utmost from rising up by the gas expelled from thehydrostatic bearings.

A differential exhausting mechanism 925 is arranged so as to surroundthe tip portion of the lens column 71 or the charged particles beamirradiating section 72, so that the pressure in a charged particles beamirradiation space 930 can be controlled so that it is sufficiently loweven if there exists high pressure in the vacuum chamber C. That is tosay, an annular member 926 of the differential exhausting mechanism 925,mounted so as to surround the charged particles beam irradiating section72, is positioned with respect to the housing 98 so that a micro gap (ofa thickness ranging from several microns to several hundred microns) 940can be formed between the lower face thereof (the surface facing to thesample) and the sample, and an annular groove 927 is formed in the lowerface thereof. That annular groove 927 is coupled to a vacuum pump or thelike (not shown), through an exhausting pipe 928. Accordingly, the microgap 940 can be exhausted through the annular groove 927 and theexhausting pipe 928, and if any gaseous molecules from the chamber Cattempt to enter the space 930 circumscribed by the annular member 926,they can be exhausted. Thereby, the pressure within the chargedparticles beam irradiation space 930 can be kept low and thus thecharged particles beam can be irradiated without any problems.

The size of said annular groove may be doubled or tripled, depending onthe pressure in the chamber C and the pressure within the chargedparticles beam irradiation space 930.

Typically, dry nitrogen is used as the high-pressure gas to be suppliedto the hydrostatic bearings. If available, however, a much higher-purityinert gas should preferably be used instead. This is because anyimpurities such as water, oil or fat included in the gas could stick onthe inner surface of the housing defining the vacuum chamber or on thesurfaces of the stage components leading to the deterioration in vacuumlevel, or could stick on the sample surface leading to the deteriorationin vacuum level in the charged particles beam irradiation space. Inaddition, a clean dry air is often used because costs are the biggestoperational reason when used in a factory. At this time, each type ofchemical filter is used in order to remove impurities, and anultra-precision filter is often used to reduce particles. For example,clean dry air is often introduced using a 1 μm filer and 3 nm filter inseries.

It should be appreciated that although typically the sample W is notplaced directly on the X table but may be placed on a sample tablehaving a function to detachably carry the sample and/or a function tomake a fine tuning of the position of the sample relative to the XYstage 93, an explanation therefor is omitted in the above descriptionfor simplicity due to the reason that the presence and structure of thesample table has no concern with the principal concept of the presentembodiment.

Since a stage mechanism of a hydrostatic bearing used in the atmosphericpressure can be used in the above described charged particles beamapparatus mostly as it is, a stage having an equivalent level ofprecision with equivalent cost and size to those of the stage ofhigh-precision fitted for a use in the atmospheric pressure, which istypically used in an exposing apparatus or the likes, may beaccomplished for an XY stage to be used in a charged particles beamapparatus.

It should be also appreciated that the configuration and arrangement ofthe hydrostatic guide and the actuator (the linear motor) have been onlyillustratively explained in the above description, and any hydrostaticguides and actuators usable in the atmospheric pressure may beapplicable. For example, a combination of a the linear motor as the Ydirection and ultrasound monitor as the x direction, or the linear motoras the y direction and an air drive positioning stage as the xdirection, or the linear motor as the y direction and a ball screw pulsemotor drive as the x direction may be applied.

FIG. 24 shows an example of numerical values representative of the sizesof the annular member 926 and the annular groove formed in the annularmember 926 of the differential exhausting mechanism. It is to be notedthat in this example, the size of the annular groove is twice that ofthe structure of 927 a and 927 b, which are separated from each other inthe radial direction.

The flow rate of the high-pressure gas supplied to the hydrostaticbearing is in the order of about 20 L/min (in the conversion into theatmospheric pressure). Assuming that the vacuum chamber C is exhaustedby a dry pump having an exhaust velocity of 20000 L/min via a vacuumpipe having an inner diameter of 50 mm and a length of 2 m, the pressurein the vacuum chamber C will be about 160 Pa (about 1.2 Torr). At thattime, with the applied size of the annular member 926, the annulargroove and others of the differential exhausting mechanism as describedin FIG. 24, the pressure within the charged particles beam irradiationspace 930 can be controlled to 10⁻⁴ Pa (10⁻⁶ Torr).

FIG. 25 shows a further embodiment of the XY stage. A vacuum chamber Cdefined by a housing 98 is connected with a dry vacuum pump 953 viavacuum pipes 974 and 975. An annular groove 927 of a differentialexhausting mechanism 925 is connected with an ultra-high vacuum pump ora turbo molecular pump 951 via a vacuum pipe 970 connected to an exhaustport 928. Further, the interior of a lens column 71 is connected with aturbo molecular pump 952 via a vacuum pipe 971 connected to an exhaustport 710. Those turbo molecular pumps 951 and 952 are connected to thedry vacuum pump 953 through vacuum pipes 972 and 973. (In the diagram,the single dry vacuum pump is used to serve both as a roughing vacuumpump of the turbo molecular pump and as a pump for vacuum exhausting ofthe chamber, but multiple dry vacuum pumps of separate systems may beemployed for exhausting, depending on the flow rate of the high-pressuregas supplied to the hydrostatic bearings of the XY stage, the volume andinner surface area of the vacuum chamber and the inner diameter andlength of the vacuum pipes.)

A high-purity inert gas (N₂ gas, Ar gas or the like) is supplied to ahydrostatic bearing of an XY stage 93 through flexible pipes 921 and922. The gaseous molecules expelled from the hydrostatic bearing arediffused into the vacuum chamber and exhausted by the dry vacuum pump953 through exhaust ports 919, 920 a and 920 b. Further, the gaseousmolecules that have entered the differential exhausting mechanism and/orthe charged particles beam irradiation space are sucked from the annulargroove 927 or the tip portion of the lens column 72 through theexhausting ports 928 and 710 to be exhausted by the turbo molecularpumps 951 and 952; then, after having been exhausted by the turbomolecular pumps, the gaseous molecules are further exhausted by the dryvacuum pump 953.

In this way, the high-purity inert gas supplied to the hydrostaticbearing is collected in the dry vacuum pump and then exhausted.

On the other hand, the exhaust port of the dry vacuum pump 953 isconnected to a compressor 954 via a pipe 976, and the exhaust port ofthe compressor 954 is connected to flexible pipes 931 and 932 via pipes977, 978 and 979 and regulators 961 and 962. As a result of thisconfiguration, the high-purity inert gas exhausted from the dry vacuumpump 953 is compressed again by the compressor 954 and then the gas,after being regulated to an appropriate pressure by the regulators 961and 962, is supplied again to the hydrostatic bearings of the XY stage.

In this regard, since the gas to be supplied to the hydrostatic bearingsis required to be as highly purified as possible in order not to haveany water contents or oil and fat contents included therein, asdescribed above, the turbo molecular pump, the dry pump and thecompressor must have structures that prevent any water contents or oiland fat contents from entering the gas flow path. It is also consideredeffective for a cold trap, filter or the like (960) to be provided alongthe outlet side piping 977 of the compressor so as to trap anyimpurities such as water, oil or fat contents included in thecirculating gas and prevent them from being supplied to the hydrostaticbearings.

This may allow the high purity inert gas to be circulated and reused,and thus allows the high-purity inert gas to be saved, while the inertgas would not remain desorbed into a room where the present apparatus isinstalled, thereby eliminating a fear that any accidents such assuffocation or the like would be caused by the inert gas.

It is to be noted that a circulation piping system is connected with thehigh-purity inert gas supply system 963, said system 963 serving notonly to fill up, with the high-purity inert gas, all of the circulationsystems including the vacuum chamber C, the vacuum pipes 970 to 975, andthe pipes in compression side 976 to 980, prior to the commencement ofthe gas circulation, but also to supply gas if the flow rate of thecirculation gas decreases for some reason.

Further, a single dry vacuum pump 953, if provided with a function tocompress to a level equal to or greater than the atmospheric pressure,may be used as both the dry vacuum pump 953 and the compressor 954.

Further, as to the ultra-high vacuum pump to be used for exhausting thelens column, other pumps including an ion pump and a getter pump may beused instead of the turbo molecular pump. It is to be noted that in thecase where reservoir type pumps are used, it is prohibited to buildcirculation systems in those areas. It is also evident that instead ofthe dry vacuum pump, other type of dry pumps, for example, a dry pump ofdiaphragm type, may be used.

Second Embodiment

Here, FIG. 26A is referred to. FIG. 26A is a schematic diagram of anoptical system used in the electron-optical device 70 of the inspectiondevice 1 of the present invention related to the present embodiment. Theelectron-optical device 70 includes a light source 10000, a mirror 10002and 10004, a lens optical system 724 (lenses 724-1 and 724-2),electrostatic lenses 10006 and 10009, numerical aperture 10008,electrostatic lens optical system 741 and a detection system 76. In thepresent embodiment, a UV laser beam source may be used as the lightsource 10000, however, as in the first embodiment, other light sourcesmay be used if a photoelectron beam is emitted from a substrate which isirradiated with light from a light source such as UV, DUV, EUV light andlaser, and X ray and X ray laser etc. Furthermore, the same referencesymbols are used for the same structural components as the firstembodiments.

Two laser beams are generated from the light source 10000 and each areirradiated to the mirrors 10002 and 10004, reflected by the mirrorsreflection surfaces, and bent in a forward direction to a wafer WF on astage device 50. The laser beam reflected by the reflection surface ofthe mirrors 10002 and 10004 pass through the lens optical system 724 andis irradiated as a primary beam onto the wafer WF on the stage 50. A twodimensional image produced by secondary emitting photoelectronsgenerated by the primary beam irradiated on the wafer is formed at alocation of a field stop, after passing between the mirrors 10002 and10004 and passing through numerical aperture 10008 via theelectro-static lenses 10006, 10009 and magnified and projected by asubsequent stage of lens 741 and detected by the detection system 76.

FIG. 27A is a schematic diagram of the electron-optical device 70 of theinspection device 1 of the present invention related to the presentembodiment. In the present embodiment, apart from the structure of theprimary lens system being different to the first embodiment, theremaining structure is the same and a reference may be made to theexplanation of FIG. 9 in the first embodiment. In addition, in FIG. 26and FIG. 27, an example of mentioned above uses the introduction of twolaser beams being introduced, however, single laser beam may also beused. For example, in FIG. 26B, FIG. 27B, light or a laser is generatedfrom the light source 10000, single laser beam 10000A is reflected bythe mirror 10002 in the secondary optical system and arrives at thesample surface (there is no 10000B). At this time, for example, themirror arranged within the secondary optical system is at positionseparate from the center axis of the secondary optical system of about1˜10 mm, and the reflection position of the mirror is also at a positionseparate from the center axis of the secondary optical system.Consequently, the irradiation angle to the sample is not perpendicularbut is slanted. When the angle with respect to the secondary opticalsystem axis (x axis) is θp, the irradiation light is irradiated onto thesample surface at this angle θp. With this method, light is irradiatedonto a single edge of an uneven structure, and the other edge part fallsinto shadow and is difficult to irradiate. In this way, the contrast ofone edge is increased and it is possible to take an image of an unevenstructure pattern. In addition, not limited to two laser beams but aplurality of laser beams are possible. In the case of a plurality oflaser beams, irradiation with more uniform beam can be performed becausea laser with a different angle θp or light introduction image ispossible. In addition, a beam with a strong bias can also be irradiated.A laser or light beams for example can have between 3˜20 beams, and evenmore is possible. Uniformity improves when irradiation of an object atthe center axis of the secondary optical system is performed, and anelectron image having high uniformity can be obtained. Also, when aplurality of lasers or light beams are asymmetrically irradiated, a beamwith a strong bias is irradiated. At this time, an image can be obtainedhaving a locally high contrast. Alternatively, as is shown in FIG. 26C,the mirror has a single unit structure and it is possible to use themirror with single laser beam or a plurality of laser beams. Forexample, a triangular unit structure with a hole at the center and aninclined surface has a mirror function. At this time, it is important tobe able to coat the surface with a conductive material or be formed froma conductive material. Photoelectrons from the sample surface passthrough the hole at the center. Consequently, when there is aninsulation material bad effects are produced such as a change intrajectory or deterioration in aberration caused by a potential changedue to charge up. The hole has a cross sectional shape but often hascircular shape and may also have an angular shape. An axis object shapeis preferred. A pentagon shape where all the surfaces are angular, or ashape in which the inclined surface and upper surface are planar and theside surfaces are curved is also possible. What is important is thatsurface roughness (for example, average surface roughness R) of theinclined surface having a mirror function is smaller than the wavelengthof the irradiated laser or light. About ½˜ 1/16 is preferred. When thesurface roughness is larger than the wavelength, scattered lightincreases and reflection ratio decreases which leads to a drop inefficiency. In addition, in the structure of the mirror, even in twobeams irradiation or a plurality of beams irradiation as shown in FIGS.26, 27 and 29, the number of parts may be this single mirror. The mirrorpart 10002 and mirror part 10004 may be a single unit mirror.Specifically, it is possible to coat the mirror surface and other partwith aluminum when the base material is a glass. At this time, thesurface roughness of the mirror surface is a value smaller than thewavelength as mentioned above. In addition, either one of Au, Ru, Os,carbon, Pt, Ti or Cr may be coated or a plurality of materials may becoated in an electrode thin film state on the aluminum coat of themirror surface.

Third Embodiment

In the present embodiment, the optical system for irradiating lightgenerated from the light source 10000 to a substrate is different to theoptical system used in the electron-optical device 70 of the inspectiondevice 1 of the present invention related to the second embodiment.Other structural elements are the same as in the second embodiment andtherefore their explanation is omitted here.

FIG. 28 is referred to. FIG. 28 is s a schematic diagram of an opticalsystem used in the electron-optical device 70 of the inspection device 1of the present invention related to the present embodiment. Theelectron-optical device 70 related to the present embodiment includes alight source 10000, a fiber plate 11000A and 11000B, a hole part 11002,a lens optical system 724 (lenses 724-1 and 724-2), electrostatic lenses10006 and 10009, numerical aperture 10008, electrostatic lens opticalsystem 741 and a detection system 76. In the present embodiment, a UVlaser beam source may be used as the light source 10000, however, as inthe first embodiment, other light sources may be used if a photoelectronbeam is emitted from a substrate which is irradiated with a light from alight source such as UV, DUV, EUV light and laser, and X ray and X raylaser etc. Furthermore, the same reference symbols are used for the samestructural components as the first embodiments.

Laser beam is generated from the light source 10000 and irradiated toeach fiber plate 11000A and 11000B. The light irradiated to the fiberplates 11000A and 11000B is bent in a forward direction to a wafer WF ona stage device 50, passes through the lens optical system 724 and isirradiated as a primary beam onto the wafer WF on the stage 50. A twodimensional image produced by photoelectrons generated by the primarybeam irradiated on the wafer is formed at a location of a field stop,after passing through the hole part 11002 and passing through numericalaperture 10008 via the electro-static lenses 10006, 10009 and magnifiedand projected by a subsequent stage of lens 741 and detected by thedetection system 76.

Fourth Embodiment

In the present embodiment, the optical system which leads atwo-dimensional secondary electron image generated by a primary beamirradiated onto a wafer is different to the optical system used in theelectron-optical device 70 of the inspection device 1 of the presentinvention related to the second embodiment. Other structural elementsare the same as in the second embodiment and therefore their explanationis omitted here.

FIG. 29A is referred to. FIG. 29A is s a schematic diagram of an opticalsystem used in the electron-optical device 70 of the inspection device 1of the present invention related to the present embodiment. Theelectron-optical device 70 related to the present embodiment includes alight source 10000, mirrors 10002 and 10004, a lens optical system 724,a correction lens 12000, numerical aperture 10008, a fiber plate 11000Aand 11000B, electrostatic lens optical system 741 and a detection system76. In the present embodiment, a UV laser beam source may be used as thelight source 10000, however, as in the first embodiment, other lightsources may be used if a photoelectron beam is emitted from a substratewhich is irradiated with a light from a light source such as UV, DUV,EUV light and laser, and X ray and X ray laser etc. Furthermore, thesame reference symbols are used for the same structural components asthe first embodiments.

Two laser beams (10000A and 10000B) are generated from the light source10000 and each are irradiated to the mirrors 10002 and 10004, reflectedby the mirrors reflection surfaces, and bent in a forward direction to awafer WF on a stage device 50. The laser beam reflected by thereflection surface of the mirrors 10002 and 10004 pass through the lensoptical system 724 and is irradiated as a primary beam onto the wafer WFon the stage 50. A two-dimensional image produced by secondary emittingelectrons generated by the primary beam irradiated on the waferconverges at a location of the numerical aperture (NA) 10008 via thecorrection lens 12000 after passing between the mirrors 10002 and 10004and a cross over is formed. The image is magnified and projected by asubsequent stage field lens 12002, a zoom lens 12004, a zoom lens 12006and the electro-static lens system 741 and detected by the detectionsystem 76. Off-axis aberration is corrected by the field lens 12002,continuous magnification setting becomes possible using the zoom lensesand an image is formed in the detector by the electro static lenses 741,magnified and projected. Furthermore, in the present embodiment, 1system laser may be introduced as is shown in FIG. 29B. The effects inthis case are the same as the effects explained using FIG. 26B and FIG.27B.

Fifth Embodiment

In the present embodiment, the optical system for irradiating lightgenerated from the light source 10000 to a substrate is different to theoptical system used in the electron-optical device 70 of the inspectiondevice 1 of the present invention related to the second embodiment.Other structural elements are the same as in the second embodiment andtherefore their explanation is omitted here.

FIG. 30 is referred to. FIG. 30 is s a schematic diagram of an opticalsystem used in the electron-optical device 70 of the inspection device 1of the present invention related to the present embodiment. Theelectron-optical device 70 related to the present embodiment includes alight source 10000, a fiber plate 11000A and 11000B, a hole part 11002,a lens optical system 724 (cathode lenses 724-1 and 724-2 (not shown inthe diagram)), correction lens 12000, numerical aperture (NA) 10008,field lens 12002, zoom lens 12004, zoom lens 12006, electrostatic lensoptical system 741 and a detection system 76. In the present embodiment,a UV laser beam source may be used as the light source 10000, however,as in the first embodiment, other light sources may be used if aphotoelectron beam is emitted from a substrate which is irradiated witha light from a light source such as UV, DUV, EUV light and laser, and Xray and X ray laser etc. Furthermore, the same reference symbols areused for the same structural components as the first embodiments.

Two laser beams is generated from the light source 10000 and irradiatedto each fiber plate 11000A and 11000B. The light irradiated to the fiberplates 11000A and 11000B is irradiated as a primary beam onto the waferWF on the stage 50 after passing through the lens optical system, 724. Atwo dimensional image produced by secondary emitting electrons generatedby the primary beam irradiated on the wafer is formed at a location of afield stop via the correction lens 12000 and is magnified and projectedby a subsequent stage field lens 12002, zoom lens 12004, zoom lens 12006and the electro-static optical system 741 741 and detected by thedetection system 76.

Sixth Embodiment

In the present embodiment, the optical system is different to theoptical system used in the electron-optical device 70 of the inspectiondevice 1 of the present invention related to the second embodiment inthe point where a plurality of lights having different wavelengths areirradiated to a substrate. Other structural elements are the same as inthe second embodiment and therefore their explanation is omitted here.

FIG. 31 is referred to. FIG. 31 is s a schematic diagram of an opticalsystem used in the electron-optical device 70 of the inspection device 1of the present invention related to the present embodiment. Theelectron-optical device 70 related to the present embodiment includes alight source 10000A (wavelength λ1) and 10008 (wavelength λ2), mirrors10002 and 10004, a lens optical system 724 (cathode lenses 724-1 and724-2), electrostatic lenses 10006, 10009, numerical aperture (NA)10008, and electrostatic lens optical system 741 and a detection system76. In the present embodiment, a DUV laser beam source may be used asthe light source 10000A and light source 10000B, however, as in thefirst embodiment, other light sources may be used if an photoelectronbeam is emitted from a substrate which is irradiated with a light from alight source such as UV, DUV, EUV light and laser, and X ray and X raylaser etc. Furthermore, the same reference symbols are used for the samestructural components as the first embodiments.

Two laser beams having different wavelengths, A (wavelength λ1) and B(wavelength λ2) are generated from the light source 10000A and 10000Band each are irradiated to the mirrors 10002 and 10004, reflected by themirrors reflection surfaces, and bent in a forward direction to a waferWF on a stage device 50. The laser beam reflected by the reflectionsurface of the mirrors 10002 and 10004 pass through the lens opticalsystem 724 and is irradiated as a primary beam onto the wafer WF on thestage 50. The laser beams having different wavelengths A (λ1) and B (λ2)may be irradiated onto the wafer simultaneously or alternatelyirradiated. A two dimensional secondary electron image generated by theprimary beam irradiated on the wafer is formed at a location of a fieldspot after passing between the mirrors 10002 and 10004, passing throughthe numerical aperture 10008 via the electrostatic lenses 10006 and10009, magnified and projected by the subsequent stage lens 741 anddetected by the detector system 76.

Furthermore, in the present embodiment, a light source having twodifferent wavelengths was used, however, a light source having more 2 ormore different wavelengths may also be used.

Seventh Embodiment

In the present embodiment, the irradiation direction of light from alight source to a wafer substrate is different to the optical systemused in the electron-optical device 70 of the inspection device 1 of thepresent invention related to the second embodiment. Other structuralelements are the same as in the second embodiment and therefore theirexplanation is omitted here.

FIG. 32A is referred to. FIG. 32A is s a schematic diagram of an opticalsystem used in the electron-optical device 70 of the inspection device 1of the present invention related to the present embodiment. Theelectron-optical device 70 related to the present embodiment includes alight source 10000, a lens optical system 724 (cathode lenses 724-1 and724-2), electrostatic lenses 10006, 10008, numerical aperture 10008,electrostatic lens optical system 741 and a detection system 76. In thepresent embodiment, a DUV laser beam source may be used as the lightsource 10000, however, as in the first embodiment, other light sourcesmay be used if a photoelectron beam is emitted from a substrate which isirradiated with a light from a light source such as UV, DUV, EUV lightand laser, and X ray and X ray laser etc. Furthermore, the samereference symbols are used for the same structural components as thefirst embodiments.

In FIG. 32A (a), laser 10000A is generated from the light source 10000and irradiated as a primary beam on the back surface of the sample W onthe stage device 50. When the laser 10000A irradiated as a primary beamis irradiated onto the sample W, a two dimensional secondary electronimage which follows the pattern on the wafer is produced, and the twodimensional image of the photoelectron beam passes through the cathodelenses 724-1 and 724-2, is converged by the electrostatic lens 10006, across over is formed in the vicinity of a location of the numericalaperture (NA) 10008, and the electrostatic lenses 10006 and 10009include a zoom function which can control the magnification. Followingthis, the image is magnified and projected by the subsequent stage lens741 and detected by the detector system 76.

FIG. 32A (b) shows photoelectrons being emitted from the surface P1 andP2 of a wafer W. At this time, when P1 is a material which allowsphotoelectrons to be easily generated and P2 is a material which doesnot allow photoelectrons to be easily generated, many photoelectrons aregenerated from P1 by laser irradiation from the back surface, while onlya few photoelectrons are generated from P2. Therefore, a pattern havinga contrast due to photoelectrons can be obtained with respect to apattern shape formed by P1 and P2.

The example shown in FIG. 32A above used irradiation of a laser or lightfrom the back surface of a sample. However, an example of an embodimentwhere a laser or light is irradiated from the front surface is describedin FIG. 32B, FIG. 32C, FIG. 32D and FIG. 32E. The laser or light whichis used is a DUV laser beam source, however, as in the first embodiment,other light sources may be used if an photoelectron beam is emitted froma substrate which is irradiated with a light from a light source such asUV, DUV, EUV light and laser, and X ray and X ray laser etc.

FIG. 32B and FIG. 32C include the same devices, irradiation system andsecondary optical system as FIGS. 8, 9, 26A, 27A and 29A. In addition,in FIG. 32B and FIG. 32C and example is shown whereby a contrast isformed when the sample has asperities, the amount of photoelectronsemitted from the hollow and bump parts is different, and an image havinga high resolution is possible. When the material of the sample unevenstructure parts is different, the amount of photoelectrons emitted fromthe hollow part is more than the bump part and the reverse is often truedue to the wavelength of primary beam irradiation. While a more detailedexample is explained below, this is an example where a high resolutioncan be achieved due to the difference in the amount of emittedphotoelectrons.

In addition, FIG. 32D and FIG. 32E show image formation by thedifference in the amount of photoelectrons from the sample surfacehaving asperities, and also shown an example in the case where a primarybeam irradiation system irradiates at a different angle the same as isshown in FIG. 32B and FIG. 32C. While FIG. 32B and FIG. 32C show anexample in the case where irradiation is performed at an angle almostperpendicular to the surface of the sample, FIG. 32D and FIG. 32E showan example in the case where irradiation is performed at a slantedangle. In this case, the primary beam is introduced using a laser,mirror and lens, however, it is also possible to irradiate the surfaceof a sample using fiber. In the case, of a short wavelength such as UV,DUV, EUV and X rays, the transmittance rate of a laser or light issometimes poor in a usual silica fiber. Laser or light can betransmitted efficiently by using hollow fiber or a hollow pipe.

In addition, as described above, with respect to the irradiation angleof a primary beam, because a sample having a pattern sometimes receivesthe effects of an angle, at this time, optimization of the angle oflight or laser angle which is irradiated, that is, the best S/N of apattern defect or conditions with high contrast are selected and it ispossible to select the angle at which to irradiate which us important

Eighth Embodiment

Electron Optical Device arranged with a primary optical system using inelectron irradiation instead of a primary system used in lightirradiation.

Irradiating a sample surface with light or a laser has been described upto this point, and the generation of photoelectrons from the samplesurface. Here, instead of irradiating light, an embodiment of a primarysystem which irradiates an electron beam is described. First, an exampleof an inspection device arranged with a general electron gun (beamgenerator) is shown in FIG. 33. FIG. 33 (a) show the entire structure,FIG. 33 (b) is an exploded schematic diagram of an electron gun part.However, a partial structure has been omitted.

In FIG. 33 (a), the inspection apparatus has a primary column 71-1, asecondary column 71-2 and a chamber 32. An electron gun 721(beamgenerator) is arranged on the inside of the primary column 71-1, and aprimary optical system 72 is disposed along the optical axis of anelectron beam (a primary electron beam) irradiated from the electron gun721. Further a stage 50 is installed in the interior of the chamber 32and a sample W is loaded on the stage 50. On the other hand, in theinterior of the secondary column 71-2, a cathode lens 724, a numericalaperture NA-2, a Wien filter 723, a second lens 741-1, a field apertureNA-3, a third lens 741-2, a fourth lens 741-3 and a detector 761 arelocated on the optical axis of the secondary electron beam emanatingfrom the sample W. It is to be noted that the numerical aperture NA-3corresponds to an aperture diaphragm, which is a thin plate made ofmetal (Mo or the like) having a circular aperture formed therein.Herein, the numerical aperture NA-2 is arranged with an aperture sectionso as to be at a focused location of the primary electron beam and alsoat a focusing location of the cathode lens 724. Accordingly, the cathodelens 724 and the numerical aperture NA-2 construct a telecentricelectronic optical system. In particular, the cathode lens 724 sometimesforms both telecentric electron optical systems in which a firstintermediate image forming point is formed near the ExB center by a twostage tablet lens. Compared to a single telecentric or no telecentric itis possible to reduce aberration and achieve two dimensional electronimage with a wide field and high resolution image forming. That is, itis possible to realize ½˜⅓ the aberration.

On the other hand, the output from the detector 761 is input into acontrol unit 780, and the output from the control unit 780 is input intoa CPU 781. A control signal from the CPU 781 is input into a primarycolumn control unit 71 a, a secondary column control unit 71 b and astage driving mechanism 56. The primary column control unit 71 acontrols a lens voltage in the primary optical system 72, and thesecondary column control unit 71 b controls lens voltages in the cathodelens 724 and the second lenses 741-1 to the fourth lens 741-3 and alsoan electromagnetic field applied to the Wien filter 723. Further, thestage driving mechanism 56 transmits position data of the stage to theCPU 781. Still further, the primary column 71-1, the secondary column71-2 and the chamber 32 are connected to the vacuum exhausting system(not shown in the diagram) and exhausted by a turbo pump in the vacuumexhausting system so as for the interior thereof to be maintained invacuum.

(Primary Beam)

The primary electron beam from the electron gun 721(beam generator)enters into the Wien filter 723 while receiving a lens effect caused bythe primary optical system 72. Herein, LaB6 may be used for a chip ofthe electron gun, which is a rectangular or elliptical flat, curvedsurface (for example about r=50 μm) and from which a high current can beemitted. Further, the primary optical system 72 may use an electrostatic(or electromagnetic) quadrupole or octopole lens, asymmetric withrespect to a rotating axis. This lens, similar to what is called acylindrical lens, can cause a focusing and a divergence in the X and theY axes respectively. Such a configuration comprising two or three stepsof these lenses to optimize respective lens conditions allows the beamirradiation region on the sample surface to be formed into a rectangularor elliptical shape as desired without any loss of irradiated electrons.Specifically, in the case of the electrostatic lenses being used, fourcylindrical rods may be used. Each two opposite electrodes are made tobe equal in potential and reverse voltage characteristics are giventhereto. It is to be appreciated that a lens formed in the shape of aquarter of a circular plate used commonly in the electrostaticdeflector, rather than the cylindrical shape, may be used for thequadrupole lens. That case allows for the miniaturization of the lens.

The primary electron beam after passing through the primary opticalsystem 72 is forced by the deflecting effect from the Wien filter 723 soas to deflect the trajectory thereof. In the Wien filter 723, themagnetic field is crossed with the electric field at right angles, andonly the charged particles satisfying the Wien condition of E=vB areadvanced straight ahead, and the orbits of the other charged particlesare deflected, where the electric field is E, the magnetic field B, andthe velocity of the charged particle v. A force FB by the magnetic fieldand another force FE by the electric field may be generated against theprimary beam, and consequently the primary beam is deflected. On theother hand, the force FB and the force FE are reversely applied to thesecondary beam and those forces are cancelled to each other, so that thesecondary beam is allowed to go directly forward. A lens voltage of theprimary optical system 72 has been determined beforehand such that theprimary beam is formed into an image at the aperture portion of thenumerical aperture NA-2. That numerical aperture NA-2 prevents anyexcess electron beams to be dispersed in the apparatus from reaching tothe sample surface and thus prevents charging or contamination in thesample W. Further, since the numerical aperture NA-2 and the cathodelens 724 together form the telecentric electronic optical system, theprimary beams that have passed through the cathode lens 724 may turn tobe parallel beams, which are irradiated uniformly and similarly againstthe sample W. That is to say, it accomplishes what is called in anoptical microscope, the Koehler illumination.

(Secondary Beam)

When the primary bean is irradiated against the sample, secondaryelectrons, reflected electrons or back-scattering electrons aregenerated as the secondary beam from the beam irradiated surface of thesample. The secondary beam passes through the lens while receiving alens effect from the cathode lens 724. It is to be noted that thecathode lens 724 is composed of three or four electrodes. Among thoseelectrodes, the one at the lowest position is designed to form apositive electric field between the potentials in the sample W side anditself, and to take in electrons (particularly, secondary emittingelectrons with smaller directivities and mirror electrons) so that theelectrons may be efficiently introduced into the lens. Further, the lenseffect takes place in such a way that voltages are applied to the firstand the second electrodes of the cathode lens 724 and the thirdelectrode is held to zero potential. Alternatively, a voltage is appliedto the first, second and third electrodes and the fourth electrode isheld to zero potential. The third electrode is used for focus adjustmentwhen there are four electrodes. On the other hand, the numericalaperture NA-2 is disposed at the focal position of the cathode lens 724,that is, the back focal position with respect to the sample W.Accordingly, the trajectories of electron beams originating from thecenter of the field of view (off-axis) also become the parallel beamsand pass through the central location in this numerical aperture NA-2without being kicked out any further. It is to be appreciated that thenumerical aperture NA-3 serves to reduce lens aberrations of the cathodelens 724, second lens 741-1 to the fourth lens 741-3 for the secondarybeams. Those secondary beams having passed through the numericalaperture NA-2 may not affected by the deflecting effect from the Wienfilter 723 but may keep on going straight through the filter. It is tobe noted that varying the electromagnetic field applied to the Wienfilter 723 may allow only electrons having specified energies (forexample, secondary electrons, reflected electrons or back-scatteringelectrons) to be introduced into the detector 761. The cathode lens 724is an important lens for determining aberration of the secondaryemitting electrons generated form the sample surface. Consequently, alarge magnification can not be expected. Therefore, a dual telecentricstructure is formed as a cathode lens having a two stage tablet lensstructure in order to reduce aberration. Furthermore, an intermediateimage formation for reducing aberration (astigmatism etc) which isgenerated by the Wien filter formed by ExB, is set near the centerlocation vicinity of ExB. In this way, the effect of controlling anincrease in aberration is significant. Also, beams are converged by thesecond lens 741-1 and a cross over if formed near the vicinity of thenumerical aperture NA-3. A zoom lens function is obtained by the secondlens 741-1 and third lens 741-2, a control of magnification becomespossible. The fourth lens 741-3 exists at this subsequent stage and amagnified image is formed on the surface of the detector. The fourthlens has a five stage lens structure with stages 1, 3, 5 being grounded.A positive high voltage is applied to the second and fourth stages and alens is formed. At this time, the second stage includes a field lensfunction and second intermediate image forming is performed in thisvicinity. At this time, it is possible to correct off-axis aberrationusing the field lens function. In this way, here, image forming isperformed a total of three times. Furthermore, the cathode lens 724 maybe combined with the second lens 741-1 to form an image on the detectorsurface (total of two times). In addition, each of the second lens 741-1to the fourth lens 741-3 should be a lens symmetrical with respect to arotating axis of the kind referred to as a uni-potential lens or Einzelllens. Each lens is composed of three electrodes, in which typically theouter two electrodes have zero potentials and a voltage applied to thecenter electrode is used to causes a controlling lens effect. Further, afield aperture FA-2 (not shown in the diagram) is located in theintermediate image forming point. This field aperture FA-2 is arrangednear the second stage when the fourth lens 741-3 has five lens stages,and is arranged near the first stage when the fourth lens 741-3 hasthree lens stages. The field aperture FA-2 which constrains the field ofview to be limited to a required range, similar to a field stop in anoptical microscope, for the case of an electron beam, cooperativelyblocks any excess beams so as to prevent charging and/or contaminationof the detector 761. The secondary beam is magnified and projected bythe secondary optical system and formed into an image on the detectionplane of the detector 761. The detector 761 comprises a MCP foramplifying an electron, a fluorescent screen for converting theelectrons into light, lenses and other optical elements for use as arelay and transmitting an optical image between the vacuum system andexternal components, and an image sensor (CCD or the like). Thesecondary beam is formed into an image on the MCP detection plane andamplified, and then the electrons are converted into light signals bythe fluorescent screen, which are in turn converted into photo-electricsignals by the image sensor. The control unit 780 reads out the imagesignal of the sample from the detector 761 and transmits it to the CPU781. The CPU 781 performs a defect inspection of the pattern by templatematching and so forth from the image signal. On the other hand, thestage 50 is adapted to be movable in the X and Y directions by a stagedriving mechanism 56. The CPU 781 reads the position of the stage 50 andoutputs a drive control signal to the stage driving mechanism 56 todrive the stage 50, allowing for sequential detection and inspection ofthe images.

Thus, in the inspection apparatus according to the present embodiment,since the numerical aperture NA-2 and the cathode lens 724 comprise thetelecentric electron optical system, therefore the primary beam may beirradiated uniformly against the sample. That is, it accomplishes theKoehler illumination. Further, as to the secondary beam, since all ofthe principle beams from the sample W enter the cathode lens 724 at aright angle (parallel to the optical axis of the lens) and pass throughthe numerical aperture NA-2, therefore the peripheral beam would not bekicked out thus preventing deterioration of image brightness in theperiphery of the sample. In addition, although a variation of the energypertaining to the electrons gives a different focal position, whichcauses what is called a magnification chromatic aberration (especiallyfor the secondary electrons, since the energies thereof are varied to agreat extent, the magnification chromatic aberration is rather great),the arrangement of the numerical aperture NA-2 at the focal position ofthe cathode lens 724 makes it possible to control the magnificationchromatic aberration so that it is kept low.

On the other hand, since a change of the magnification factor isexecuted after the beam has passed through the numerical aperture NA-2,any changes in the determined magnification factor in the lens conditionfor the third and the fourth lenses 741-2 and 741-3 can still bring auniform image over the field of view to be obtained in the detectionside. It should be appreciated that although an even and uniform imagecan be obtained in the present embodiment, typically, increasing themagnification may problematically cause deterioration in the brightnessof the image. Accordingly, in order to improve this problematiccondition, when the lens condition for the secondary optical system ischanged to vary the magnification factor, the lens condition for theprimary optical system should be controlled such that the effectivefield of view on the sample determined in association with themagnification and the electron beam to be irradiated on the sample maybe equally sized.

That means, as the magnification is increased, consequently the field ofview gets smaller, but when the irradiation beam current of the electronbeam is increased at the same time, the signal density of the detectedelectron can be kept at a constant level and the brightness of the imagemay be prevented from deterioration even if the beam is magnified andprojected in the secondary optical system. Further, although in theinspection apparatus according to the present embodiment, a Wien filter723 has been employed, which deflects the trajectories of a primary beambut allows a secondary beam to go straight forward, the application isnot limited to this and the apparatus may employ a Wien filter withanother configuration in which the primary beam is allowed to gostraight forward but the orbit of the secondary beam is deflected. Stillfurther, although in the present embodiment, a rectangular cathode and aquadrupole element lens are used to form a rectangular beam, theapplication is not limited to this and, for example, a rectangular beamor elliptical beam may be formed from a circular beam, or the circularbeam may be passed through a slit to extract the rectangular beam.

In this example, two numerical apertures, numerical aperture NA-2 andnumerical aperture NA-3 are arranged. These can be used separatelyaccording to the amount of irradiated electrons. In the case where theamount of irradiated electrons to a sample is small, for example 0.1˜10nA, an appropriate beam diameter, for example, (φ30˜φ300 μm is used inorder to reduce aberration of the primary beam and secondary beam usingthe numerical aperture NA-2. However, when the amount of irradiatedelectrons increases, charge up occurs due to contamination beingattached to the numerical aperture NA-2 and reversely image qualitysometimes degraded. At this time, the numerical aperture NA-2 with acomparatively large hole diameter, for example, φ500˜φ3000 μm is used inthe cut of periphery stray electrons. In addition, the numericalaperture NA-3 is used for determining stipulation of aberration and rateof transmittance of the secondary beam. Few contaminants are attached tothe numerical aperture NA-3 because the primary beam is not irradiatedand there is no deterioration in image quality due to charge up.Consequently, it is extremely effective to use a numerical apertureafter selecting the numerical aperture diameter according to the size ofthe amount of irradiated electrons.

When this form of primary beam electron irradiation is performed, in thesemiconductor inspection device 1 which uses an electron gun as theprimary optical system 72 of the electron optical device 70, a problemoccurs whereby the energy band of an electron becomes wider in the caseof attempting to obtain a large irradiation current. This is explainedin detail below using the diagrams. FIG. 33 (b) is an exemplary diagramof the primary optical system 72 of the electron optical device 70arranged with a general electron gun 2300.

In the electron gun 2300 a heating current is passed through a cathode2310 via a heating power supply 2313 for generating thermal electrons.In addition, an acceleration voltage Vacc is set to the cathode 2310 byan acceleration power supply 2314. On the other hand, a voltage isapplied to an anode 2311 so that the cathode 2313 is made to have arelatively positive voltage, for example, a voltage difference of3000˜5000V. When the cathode 2310 is −5000V the anode 2311 may be 0V. Atthis time, the amount of emission is controlled by a voltage applied toa Wehnelt 2312. The Wehnelt 2312 is superimposed by the accelerationvoltage Vacc, for example, a superimposed voltage of 0˜−1000V. When thevoltage difference with Vacc is large the amount of emission decreases,and when it is small the amount of emission increases. In addition, thecross over (first cross over: 1st CO) location which can be first set bya Wehnelt voltage is misaligned in an axis direction. In addition, ifthe center of the cathode and the center of the Wehnelt, anode aremisaligned, a misalignment also occurs in a perpendicular x, y directionto the z axis, and the emitted emission becomes wider. Within this, afield aperture FA2320 selects an effective beam and beam shape. At thistime, the transmittance of to the emission is a normal ratio of0.1˜0.5%. For example, an irradiation current is 5˜25 nA when anemission is 5 μA. Consequently, for example, when attempting to obtainan irradiation current of 1 μA, an emission of 200 μA˜1 mA is required.At this time, the energy band of an electron becomes wider due to theBoersch effect in an orbit from the cathode to the first cross over andfrom the first cross over to the field aperture when the emissionbecomes large. For example it widens to 10˜50 eV from 1.2 eV at an FAposition.

Energy band becomes problematic at a low LE in particular. This isbecause the widening of an orbit of an electron near the surface of asample becomes larger in a z direction. FIG. 34 shows the intensity(amount) of an irradiation current of an electron beam irradiated to asample surface, energy state and state of a beam irradiated to a samplesurface. FIG. 34 (a) shows the intensity of an irradiation current of abeam irradiated to a sample surface and energy band, FIG. 34 (b) showsthe state of a beam irradiated to the sample surface. A beam in whichthe energy of the irradiation current of a beam irradiated to the sampleis optimized is given as beam c, a beam in which the energy of theirradiation current of a beam is low is given as beam a, and a beam inwhich the energy of the irradiation current of a beam is highest isgiven as beam b. Abeam in which the energy of the irradiation current ofa beam is high is given as beam d. The relationship between the energyof an electron beam and intensity (amount) of irradiation current isshown as the distribution in FIG. 34 (a) according to Maxelldistribution in a thermal electron shaping method such as LaB6. At thistime, an electron beam having high and low energy characteristics asdescribed above is given as beam a˜beam d.

As one example, the case where a high energy beam d is collided directlyinto the sample surface is shown in FIG. 34 (b). At this time, the beamd collides into the surface but is not reflected (no mirror reflectionshape). On the other hand, beam a, beam b and beam c are each reflectedat reflection potential points. That is, mirror electrons are formed. Inaddition, the axis direction location at which beam c, beam b and beam ahaving different energies are reflected, that is, the Z position, isdifferent. A difference ΔZ of this Z position occurs. The larger ΔZbecomes the greater image distortion becomes of an image formed by thesecondary optical system. In other words, this is because misalignmentof mirror electrons formed at the same surface position occurs in theimage forming surface. In particular, the effects are significantbecause in mirror electrons, an energy misalignment causes reflectionpoint misalignment and mid orbit misalignment. The same can also be saidfor an image forming using mirror electrons or image formation usingmirror electrons and secondary emitting electrons. Also, these badeffects become large (ΔZ becomes larger) when the energy band of anirradiated electron beam is larger. Consequently, a primary beam whichcan irradiate a sample surface in a narrow energy band state isparticularly effective. In order to achieve this, the electron generatorsupply and primary optical system is explained below using FIGS. 35˜41.Because it is not only possible to narrow the energy band of an electronbeam and dramatically increase the transmittance of a primary systembeam compared to a conventional type, it is possible to irradiate alarge current at a narrow energy band to a sample surface. That is,because it is possible to reduce ΔZ as described above, misalignment onan image formation surface in the secondary optical system becomessmaller and it is possible to realize low aberration, high resolution, alarge current and high throughput. Normally, a thermal electron type gunsuch as LaB6 includes an electron generation part with an energy band ofabout 2 eV. In addition, as the amount of current generated increases,the energy band increase further due to the Boersch effect caused by aCoulomb repulsion etc. For example, when an emission current of anelectron supply is change from 5 μA to 50 μA, the energy band widens to8.7 eV from 0.6 eV for example, that is, when the current value isincreased 10 times, the energy band becomes wider by about 15 times. Theenergy band widens due to a space charge effect etc while passingthrough the primary optical system. In order to make an electron beamwith a low energy band reach the sample surface it is very important toreduce the energy band at the electron generator, increase thetransmittance of the primary optical system and reduce the emissioncurrent at the electron generator. Although there was no means forachieving this previously, the present invention realized these effects.These effects are explained using the examples shown in FIGS. 35˜41.

In addition, the intensity (when the amount if high, beam b) of anelectron beam is not always optimized for imaging. For example, when anenergy distribution conforming to Maxell distribution is included, thebeam intensity (amount) at the part where energy is low is often thehighest (beam b). At this time, because there are many beams with ahigher energy than beam b, a different image quality to that of an imageformed by these beams is often produced. That is, when a beam d collidesinto a sample and secondary emitting electron image is formed, becausethe energy of beam d is relatively low, the effects on the unevenstructure of the sample surface are small, and mirror electrons areeasily formed, that is, the effect on uneven structure of the surface orpotential difference is small and mirror electrons are formed, therebyan image with an overall low contrast and free from glare is easilyproduced. From experience, an image with a high resolution is difficultto obtain. In particular, because the effects an amount of current whichcollides with the surface becomes larger when there is an oxide film onthe uppermost part of a surface, compared to when the emission currentis small, for example, the energy band widens by 10 times or more whenemission becomes larger (for example 10 times). At this time, when anelectron beam is irradiated to a sample surface with the same landingenergy LE, the absolute amount of a part, beam d for example, with ahigher energy than beam b which collides with the sample surfaceincreases and charge up of the oxide film becomes larger as a result.The orbit of mirror electrons or image forming conditions becomesdisordered due to the effect of this charge up and normal imaging issometimes no longer possible. This is one cause of not being able toincrease an irradiation current. Given this state, the amount of beam dwhich is collided with the sample surface is reduced and it is possibleto use beam c which has an energy which can reduce a potential change inthe oxide film (optimized energy beam). In this way, it is possible tocontrol the amount of a beam which is collided with a sample and obtaina stable image. However, as can be seen from FIG. 34 (a) beam c has alower intensity (amount) than beam b. When it is possible to bring theoptimized energy beam c closer to beam b which has the highestintensity, the amount of electrons which contribute to image formationincreases by this amount and it is possible to increase throughput. Inorder to achieve this it is important to obtain a narrow energy band andreduce the electrons which are collided with a sample surface. Thepresent invention realizes this and this is explained using the examplesin FIGS. 35˜41.

In addition, in FIG. 34 (b) when LE is gradually increased beam d iscollided with the sample surface, next beam c is collided and when thecolliding electron beam increases the secondary emitting electrons whichare thereby generated increase. A region in which mirror electrons andsecondary emitting electrons are mixed is called a transition region.When all the primary beams are collided onto a sample surface, themirror electrons disappear and only secondary emitting electrons remain.In addition, when there are no colliding electrons all the electronsbecome mirror electrons.

Furthermore, because the first cross over position changes when anemission changes by changing a Wehnelt voltage, it is necessary toadjust the aligner and lens in the lower side by this amount.

In addition, in an inspection of a semiconductor device, a 10 nm leveldefect inspection such as EUV mask inspection (extreme ultravioletlithography mask inspection) or NIL inspection (nano imprint lithographymask inspection) compatible with new technology is necessary. In orderto achieve this, a decrease in aberration and an increase in resolutionare being demanded in semiconductor inspection devices.

In order to reduce aberration and increase resolution, it is importantto reduce aberration of the secondary optical system in particular.However, a cause of deterioration in a mapping system is what is calledenergy aberration (also called color aberration) and coulomb blur. Thus,in order to improve aberration in the secondary optical system anincrease in acceleration energy in a short amount of time is demanded.

Therefore, in order to solve this problem, the inventors invented anelectron optical device which includes a primary optical system, saidprimary optical system being arranged with a new electron beamgeneration device (beam generator). This primary optical system uses DUVlight or a DUV laser as a light source. However, the light source is notlimited to this, UV, EUV or X rays may also be used. These are explainedin detail below based on FIG. 35.

As is shown in FIG. 35, the present primary optical system 2000 isarranged with a light source (not shown in the diagram), a fieldaperture (FA) 2010, a photoelectron generation device 2020(beamgenerator), an aligner 2030, an EXB deflector (Wien filter) (not shownin the diagram), an aperture 2040 and a cathode lens (CL) 2050.

The field aperture 2010 is disposed between a photoelectron surface 2021of the photoelectron generation device 2020 described herein, and alight source, and is arranged with a hole including a predeterminedshape. Light or a laser which is irradiated from the light sourcetowards the field aperture 2010 passed through the hole of the fieldaperture 2010 and is irradiated as light or a laser having the shape ofthe hole of the photoelectron surface 2021. That is, the light or laserwhich is irradiated from the light source generates a beam having thesame shape as the hole shape of the photoelectron surface 2021.Furthermore, light or a laser such as DUV (Deep ultraviolet), UV(ultraviolet), EUV (extreme ultraviolet) or X rays which have awavelength which generated a photoelectron beam is used as a lightsource.

The photoelectron generation device 2020 is arranged with aphotoelectron surface 2021, and one extraction lens comprised from athree stage extraction lens, first lens 2022, second lens 2023 and thirdlens 2024. In addition, a numerical aperture 2025 is also arranged. Amagnetic field lens or electrostatic lens is used as the extractionlens. However, in the case where a magnetic lens is used, a magneticfield corrector is arranged near the numerical aperture 2025 describedbelow. In addition, it is effective to arrange the lens near the lowerside of the field lens (not shown in the diagram) or object lens (notshown in the diagram) in the secondary optical system. An imagesometimes bends to the effects of a magnetic field and in the lens isarranged to correct this. Also, the number of extraction lenses is notlimited to the number described above.

The surface 2021 for generating photoelectrons is a base material coatedwith material for generating photoelectrons. The base material iscomprised of a light transmitting material such as quartz, silica glass,colts glass, magnesium fluoride glass etc and includes a planar surfacepart. A material having a low work function (a material having efficientphotoelectron generation) such as ruthenium, gold etc is preferably usedas the photoelectron material. In the present embodiment, aphotoelectron material such as ruthenium, gold etc is coated onto thebase material with a thickness of 1˜10 nm. The shape of thephotoelectron surface 2021 may be a 10 μm˜50 nm elliptical orrectangular shape for example but not limited to this. Light or a laseris introduced by transmittance through the viewport of the basematerial, reaches the electron surface and photoelectrons are producedin the photoelectron surface.

The extraction lens (extraction electrode) comprised form the first lens2022, second lens 2023, and third lens 2024 extract the electronsgenerated from the photoelectron surface 2021 in the opposite directionfrom the light source and the extracted electrons are accelerated. Anelectrostatic lens is used as these extraction lenses. In addition, aWehnelt is not used in the extraction lenses 2022, 2023 and 2024 and anextraction electric field is held constant. Furthermore, it ispreferable to use a single side telecentric or dual side telecentricstructure in the first extraction lens 2022, second extraction lens2023, and third extraction lens 2024. This is because it is possible toform an extremely uniform extraction electric field region and transportthe generated photoelectrons at low loss.

With respect to the voltage which is applied to each extraction lens,when a voltage V1 is applied to the electron surface, and V2, V3 and V4to the first extraction lens 2022, second extraction lens 2023, andthird extraction lens 2024 respectively, V2 and V4 are set atV1+3000˜30000V and V3 is set at V4+10000˜30000V as an example. However,the voltages are not limited to these.

A numerical aperture 2025 is arranged between the third extractionelectrode 2024 of the photoelectron generation device 2020 and analigner 2030 described below. The numerical aperture 2025 selects aformation location of a cross over, and an effective beam such as thebeam amount and aberration.

The aligner 2030 includes a first aligner 2031, second aligner 2032 andthird aligner 2033 and is used for adjustment of light axis conditions.The first aligner 2031, second aligner 2032 and third aligner 2033perform quiet operations, and fulfill the role of tilt and shift usedwhen adjusting the light axis conditions. On the other hand, the thirdaligner 2033 is used when performing a high speed operation with adynamic deflector and is used for example for a dynamic blankingoperation.

An aperture 2040 is arranged on the lower side of the aligner 2030(sample side. In the positional relationship between each part, the beamside is referred to as upper side and sample side as lower side herein).The aperture 2040 receives a beam during a blanking operation and isused in stray electron cut and beam centering. In addition, electronbeam amount measurement is possible by measurement of the absorptioncurrent of the aperture 2040.

An ExB region which is a region which intersects the secondary opticalsystem exists on the lower side of the aperture 2040 and an ExBdeflector (Wein filter) is arranged here. The ExB deflector deflects aprimary electron beam so that its optical axis is perpendicular to thesurface of the sample.

A cathode lens 2050 is arranged on the lower side of the ExB region. Thecathode lens 2050 is shared by the primary optical system and secondaryoptical system. The cathode lens 2050 may be comprised from a twostages, a first cathode lens 2051 and second cathode lens 2052, or maybe a single cathode. When the cathode lens 2050 is comprised form twostages, a cross over is formed between the first cathode lens 2051 andsecond cathode lens 2052, and a cross over is formed between the cathodelens 2050 and the sample in the case of a single cathode.

Furthermore, the amount of photoelectrons is determined by the intensityof the light or laser which is irradiated onto the photoelectronsurface. Therefore, a method for performing adjustment of the output ofa light source or laser beam source may be applied in the presentprimary optical system 2000. In addition, although not shown in thediagram, an output adjustment mechanism may be arranged between thelight source or laser beam source and the base material, for example, anattenuator or beam separator etc.

Here, the formation of a cross over in the primary optical system 2000related to present invention is described using the diagrams. FIG. 36 isan exemplary diagram of a formation of a cross over in the primaryoptical system 2000 related to present invention. FIG. 36 is exemplaryexpressed to illustrate that photoelectrons generated in thephotoelectron surface are irradiated perpendicular to the sample,however, actually the photoelectrons are deflector by the ExB deflector.

As is shown in FIG. 36, light or a laser is irradiated from a light beamor laser beam to a photoelectron surface 2021 after passing through thefield aperture 2010. The photoelectrons which are generated at thephotoelectron surface 2021 in this way form a cross over at the locationof the numerical aperture 2025, are deflected perpendicularly to thesample by the an ExB deflector via an aperture 2040 and a cross over isformed between the first cathode lens 2051 and the second cathode lens2052. Then the photoelectrons which formed this cross over areirradiated into the sample surface as an area beam. Therefore, the shapeof the electron emission of the photoelectron surface and the shape ofthe electron beam irradiated to the sample surface are conjugate. On theother hand, in the primary optical system arranged with a generalelectron gun, the photoelectrons generated from the cathode 2310 as isshown in FIG. 33 (b) form a first cross over between the cathode 2310and the anode 2311 and are irradiated into the sample surface via theanode 2311 and the field aperture 2320. Therefore, the shape of thefield aperture 2320 and the shape of the electron beam irradiated to thesample surface are conjugate.

Setting an application voltage in the primary optical system 2000related to the present invention is explained. The present invention isdifferent to a general electron gun and structure whereby light or alaser is irradiated to a photoelectron surface and the photoelectronswhich are generated are extracted by a subsequent extraction lens andaccelerated. Because there is no Wehnelt or suppressor, thephotoelectrons are accelerated by a uniform electrical field and thesetting of an application voltage to each structural element is alsodifferent to a general electron gun.

The explanation below is made using FIG. 35. Each voltage which isapplied to each structural element is as follows. V1 is applied to thephotoelectron surface 2021, V2, V3, and V4 are applied to the firstextraction electrode 2022, second extraction electrode 2023 and thirdextraction electrode 2024 which form the extraction lens respectively,V5 is applied to the numerical aperture 2025 and V6 is applied to theaperture 2040. In addition, a voltage RTD is applied to a wafer surface(also called a retarding voltage). In the primary optical system 2000 ofthe present invention, the following voltages are applied to eachstructural element when based on voltage V1 of the photoelectron surface2021. That is, in the case of a low LE, V1=RTD−10V˜RTD+5V. Y2,T4=V1+3000˜30000V. V3=V4+1000˜30000V. V5. V6=a reference potential. Inaddition, in the present embodiment of the primary optical systemrelated to the present invention, the following settings are made,RTD=5000V, V1=5005V, V2, V4=GND, V3=+20000V. It is possible to realizehigh resolution and high throughput with a low LE using these voltageapplications. However, this is only an example and the voltages appliedto each structural element are not limited to these.

Furthermore, when a reference potential is expressed as V0 and thevoltage of a surface where electrons of a detector entre is expressed asDV, the settings expressed in Table 1 below can be preferably used inthe voltage application relationship with RTD in the primary opticalsystem 2000 related to the present invention.

TABLE 1 RTD V0 DV Example 1 −30 kV 0 V −25 kV Example 2 −5 kV −25 kV 0 VExample 3 0 V −30 kV +5 kV

The electron optical device arranged with the primary optical system2000 related to the present invention having the above describedstructure can obtain the following effects.

First, the primary optical system 2000 of the present invention canrealize a very high transmittance. A transmittance of 5˜50% can besecured which is 10˜100 times the transmittance of 0.1˜0.5% of a primaryoptical system arranged with a general electron gun. This is becausefirst, since it is possible to form a very uniform extraction electricfield region with a structure comprising a planar cathode surface andnew extraction lens, it is possible to transport the formed electrons ata low loss rate. This structure can also maintain a constant extractionelectric field distribution depending on the increase or decrease in theamount of generated electrons and thereby a stable operation can berealized at a high transmittance. Since a primary optical systemarranged with a general electron gun requires a Wehnelt or suppressormechanism, and since an electric field distribution changes due to theamount of generated electrons, that is, amount of emission, and since auniform extraction electric field part becomes smaller and an effectivebeam region becomes narrower, it is difficult to increase thetransmittance. However, because the primary optical system 2000 relatedto the present invention does not require a Wehnelt or suppressormechanism, it is possible to increase the transmittance. In addition,secondly, in the primary optical system 2000 related to the presentinvention, because the location of a first cross over is on the lowerside of the lens, it is easy to arrange a numerical aperture etc andtherefore, it is possible realize an optical system where it is easy toreduce lens aberration and reduce Boersch effects. In a primary opticalsystem arranged with a general electron gun, because the location of thefirst cross over is situated in the vicinity of the Wehnelt, it isdifficult to arrange a numerical aperture at this location. In addition,because the location is misaligned due to emission, even if it ispossible to arrange a numerical aperture etc at this location forexample, it is difficult to be used effectively. In the primary opticalsystem 2000 related to the present invention, because it is possible toplace the location of the first cross over on the lower side of thelens, it is possible to remove this problem.

Second, the primary optical system 2000 related to the present inventioncan realize high throughput at a high resolution. Since a hightransmittance can be realized as described above, a very small amount ofcathode emitting current of 2˜10 μA is sufficient in order to obtain ahigh throughput, for example, an electron irradiation amount of 1 μA,Therefore, the Boersch effect can be minimized. For example, the energyband at the location of the numerical aperture is 0.5˜1.2 eV.Consequently, because it is possible to increase the amount of electronirradiation with a small energy band, misalignment of a beam formed inthe secondary optical system can be reduced and it is possible tomaintain a high resolution. These effects can realize high throughput ata high resolution.

Thirdly, the primary optical system 2000 related to the presentinvention can constantly maintain an optical system in a stable state.This is because misalignment of a first cross over in the primaryoptical system 2000 related to the present invention does not occur.

Next, the effects of the electron optical device arranged with theprimary optical system 2000 related to the present invention areexplained in detail.

First, because the primary optical system 2000 is used with thestructure described above it is possible to make the shape of anelectron beam irradiated to a sample surface 10 times to 0.1 times themagnification with respect to the electron emission shape of aphotoelectron surface. In particular, because it is possible to use theprimary optical system 2000 with reduction in magnification of ×1 orless, it is not necessary to reduce the size of the photoelectronsurface and the density of photoelectrons which are generated can bereduced and controlled. In this way, the electron optical devicearranged with the primary optical system 2000 of the present inventioncan reduce the Boersch effect and control the widening of an energyband.

Secondly, with respect to a center axis of an electron generation partof the photoelectron surface it is possible to form a photoelectrongeneration part at a center location formed at the extraction lens. Thiscan be achieved by irradiating light or a laser at this center axislocation. The location of a light source is shown in FIG. 35 and FIG. 36however it is possible to achieve the above simply by using a laser ormirror etc regardless of the location of the light source. The primaryoptical system 2000 related to the present invention is arranged withina column fixed to a main housing, however, by using light or a laser forthe generation of photoelectrons it is not necessary to always arrange alight source within the column, for example, it is possible to arrangethe light source on the exterior of the column and guide the light tothe center axis of the electron generation part on the photoelectronsurface using a mirror lens etc. Therefore, since it is possible on theatmosphere side, adjustment of the center location of the electronoptical device which uses the primary optical system 2000 related to thepresent invention is easy. In the inspection device which uses a generalelectron gun shown in FIG. 33 (b), the center locations of the cathode2310, Wehnelt 2312, anode 2311 and field aperture 2320 are misaligneddue to assembly. In addition, misalignment due to baking which isperformed after the atmosphere is released, that is, location variationafter assembly, also occurs due to undergoing a thermal expansion andcooling process due to temperature change. In order to correct thesemisalignments, a general aligner is arranged on the upper side of thefield aperture 2320 and correction is performed using the aligner. Inthe case where misalignment is significantly bad, it is necessary torepeat breakdown, assembly, adjustment and baking. On the other hand, inthe electron optical device which uses the primary optical system 2000related to the present invention, it is possible to easily form aphotoelectron generation part at a center position formed by an electrostatic lens simply by irradiating light or a laser at the center axislocation and thereby it is possible to easily make adjustments even ifmisalignment occurs due to assembly. In addition, because it is possibleto arrange a light source on the atmosphere side, variations in locationafter assembly do not occur easily and it is possible to makeadjustments easily even when they do occur after assembly. Therefore, itis possible to significantly reduce operational processes and costs.Furthermore, because it is possible to arrange the field aperture 2010which determines the electron generation shape of the photoelectronsurface on the atmosphere side, the field aperture 2010 can easily bereplaced, which also reduces operational processes and costs. When thefield aperture is arranged on the vacuum side, operations such as vacuumdamage, column breakdown, assembly, adjustment, vacuum disposal, bakingand optical axis adjustment are necessary for replacement, however, thisprocess is no longer required.

Third, the electron optical device arranged with the primary opticalsystem 2000 related to the present invention improves the level offreedom in the size of a beam. Since the electron generation shape ofthe photoelectron surface is determined by the field aperture 2010, notjust an elliptic or square shape but a rectangular shape or asymmetricshape with respect to its axis are also possible.

In the inspection device arranged with the primary optical system 2000related to the present invention, as an example a φ100 μm ellipticalshape at the photoelectron surface and a φ50 μm˜100 μm elliptical shapeat the sample surface are possible, and a 100×100 μm square shape at thephotoelectron surface and a 50×50 μm˜100×100 μm square shape at thesample surface are possible.

Fourth, in the electron optical device arranged with the primary opticalsystem 2000 related to the present embodiment, it is possible tosignificantly reduce the number of parts within a vacuum. In an electronoptical device arranged with a general electron gun, an aligner on thefront side of the field aperture 2320 shown in FIG. 33 (b) is requiredfor correcting misalignment of the center of the cathode, Wehnelt, anodeand field aperture center. In addition, 1 to 3 stage lenses are requiredfor forming a beam shape formed by field aperture 2320 on the samplesurface. Since the electron optical device arranged with the primaryoptical system 2000 related to the present invention does not requirethese parts, it is possible to significantly reduce the number of partswithin the vacuum.

If the electron optical device arranged with the primary optical systemrelated to the present invention explained above is applied to asemiconductor inspection device, it is possible to achieve highresolution and high throughput and thereby is suitable for a EUV maskinspection or NIL mask inspection. In addition, it is also possible toachieve high resolution even in the case of a low LE (landing energy).

Ninth Embodiment Second Embodiment of the Primary Optical System

A second embodiment of the primary optical system related to the presentinvention is explained. FIG. 37 is a diagram which shows a secondembodiment of the primary optical system related to the presentinvention. This primary optical system 2100 is arranged with a lightsource (not shown in the diagram), a field aperture (FA) 2110, aphotoelectron generation device 2120(beam generator), an aligner 2130,an ExB deflector (Wehnelt) (not shown in the diagram), an aperture 2140,a cathode lens (CL) 2150, a first tube 10071 and a second tube (notshown in the diagram) which houses the primary optical system. Thesecond embodiment of the primary optical system related to the presentinvention is characterized by making a reference potential a highvoltage. An explanation is given below focusing on the different pointsfrom the primary optical system related to the present inventiondescribed above.

The present embodiment includes a dual structure comprising a first tube10071 and a second tube and the photoelectron generation device 2120 isarranged with a photoelectron surface 2121, one extraction lens 2122 anda numerical aperture 2125.

The first tube 10071 is a tube for creating a reference voltage when thereference voltage is a high voltage and a high voltage is applied to thefirst tube. The first tube 10071 is arranged on so as to contact with ahole on the inner side of the hole which allows a primary beam to passthrough arranged on each of an extraction lens 2122, numerical aperture2125 and aligner 2130, the diameter of the first tube is formed largeron a latter part of the aperture 2140 and a cathode lens 2150 isarranged on the inner side of the spot where the diameter of the firsttube is formed large.

The material of the first tube 10071 is not particularly limited as longas it is not magnetic. However, a tube having the thickness of copper ora tube having the thickness of titanium, or a plastic tube which iscopper plated or titanium plated is preferred. In this way, a magneticfield is formed on the interior of the first tube 10071 when a highvoltage is applied to the first tube 10071 and a primary beam generatedat the photoelectron surface 2121 irradiated with light or a laser isaccelerated at a high speed.

On the other hand, although not shown in FIG. 37, the second tube coversthe field aperture (FA) 2110, the photoelectron generation device 2120,the aligner 2130, the ExB deflector (Wehnelt) (not shown in thediagram), the aperture 2140, the cathode (CL) 2150 and the first tube10071 and is set to GND. This becomes the outermost structure of acolumn device and therefore, this part is maintained at GND forpreventing a conduction connection with other device parts and electricshocks etc.

The extraction lens is a single lens and is an electromagnetic lens inthe second embodiment of the primary optical system related to thepresent invention. The remaining structure is the same as the firstembodiment described above and thus an explanation is omitted here.

By adopting this type of dual structure pipe in the primary opticalsystem 2100 related to the present embodiment it is possible toaccelerate at a high speed the electron beam which is generated at thephotoelectron surface 2121 by setting the sample surface voltage to GND,and adding a high voltage to the first tube 10071 which is the pipe onthe inner side of the dual pipe structure. Therefore, it is possible tocall the primary optical system related to the present invention a highacceleration column.

The voltages which are applied to each structural element in the primaryoptical system 2100 related to the present invention (refer to FIG. 37),are as follows. V1 is applied to the photoelectron surface 2121, V2 isapplied to the first tube 10071, V5 is applied to the numerical apertureNA 2225 and V6 is applied to the aperture 2140. In addition, a voltageRTD is applied to a wafer surface (also called a retarding voltage). Atlow LE conditions, V1=RTD−10V˜RTD+5V. V2, V5. V6=a reference potential.In addition, in the first embodiment of the present invention, thefollowing settings were made, RTD=0, V1=5V, reference potential=40000V.It is possible to realize high resolution and high throughput with a lowLE using these voltage applications.

At this time, when a magnetic field lens is used, a beam rotates due toa longitudinal magnetic field (remaining magnetic field in the opticalaxis direction which is generated. Consequently, the two dimensionalshape of generated photoelectrons formed at the photoelectron surfacesometimes rotate after passing through the generation part and magneticfield lens. In order to correct this, a rotation correction lens isarranged near the NA or at a location on the lower side of the magneticfield lens and the effects are corrected. The correction lens located onthe lower side of the magnetic field lens is preferred to be arranged ata location (directly after) as near as possible to the magnetic fieldlens and correct the rotation.

In addition, in the primary optical system 2000 of the electrostaticlens of the present invention (refer to FIG. 35) when describing theexample of a dual tube structure based on the voltage V1 of thephotoelectron surface 2021 each of the structural elements is appliedwith a voltage as follows. That is, in the case of a low LEV1=RTD−10V˜RTD+5V. V2, V5, V6 are reference potentials, and V3=referencevoltage+10˜100 kV. In addition, in one example of the present invention,the settings are as follows; RTD=0, V1=−5V, V2=referencepotential+40000V, and V3=65000V. Also, there is a first tube installedwith these lenses so that a reference voltage becomes a reference spacevoltage and the lens, aperture and aligner of FIG. 35 are installedwithin the first pipe in which the reference voltage is applied. Inaddition, a second tube which includes a GND potential is arranged onthe exterior. An insulation part is fixed between the first and secondtubes. (The first and second tubes are not shows in the diagram). A highresolution and high throughput at a low LE can be realized by thevoltage applications described above.

The primary optical system 2100 related to the present invention canobtain the effect of being able to perform an inspection while a samplesurface voltage RTD remains at 0V. Furthermore, the primary opticalsystem 2100 related to the present invention can also obtain the sameeffects as the primary optical system 2000 related to the presentinvention described above. In addition, because the effects of theelectron optical device arranged with the primary optical system relatedto the present invention are also the same an explanation is omitted.

Modified Example of a Photoelectron Generation Device in the PrimaryOptical System

Another example of a photoelectron generation device in the primaryoptical system related to the present invention is shown. FIG. 38 andFIG. 39 are examples when light or a laser is guided to a photoelectronsurface from a midpoint device of the primary system by a mirrorarranged within a column.

FIG. 38 is an example when a reference voltage is a high voltage, forexample, 40 kV. That is, an example applied to a second embodiment ofthe primary optical system 2000 related to the present invention. Atthis time, a voltage of V2=40 kV is applied to a tube 10071 which isapplied with a high voltage for forming a reference voltage. Theinterior of the tube 10071 has the same voltage space. Therefore, inthis example, DUV light or a UV laser is introduced by passing throughthe hole arranged in the tube 10071 which is not shown in the diagramusing a mirror with a hole at a center part through which photoelectronspass, for example, a triangular mirror 2170, reflected by the triangularmirror 2170 and irradiated to the photoelectron surface 2121. Inaddition, photoelectrons are generated from the surface which isirradiated, and these photoelectrons pass through an EX lens 2120 andthe NA 2125 and an aligner located the lower side are irradiated to thesample surface. At this time a voltage having a specified value isapplied to the photoelectron surface 2121 in order for thephotoelectrons to form an orbit around the primary system, which isdetermined by LE=RTD voltage−V1.

On the other hand, FIG. 39 shows an example where light or a laser whichgenerated photoelectrons is irradiated to a photoelectron surface via atriangular mirror 2070 the same as the example shown in FIG. 38, and isan example of a reference voltage GND. That is, an example applied tothe first embodiment of the primary optical system 2000 related to thepresent invention. At this time, for example, V2, V4 and V5 are set toGND and the area in this vicinity is a reference voltage space. Inaddition, it is possible to arrange a mirror similar to FIG. 38 andintroduce light or a laser. At this time, the amount of photoelectronswhich are generated is determined by the irradiation intensity of thelight or laser and therefore control of the irradiation intensity isperformed. The intensity control method previously mentioned is used forthis. At this time, the mirror surface and entire structure is aconductor or coated with a conductor. Also, the potential is the same asa reference potential so that the space potential is not distorted. Inaddition, so that a primary beam can pass through without being affectedby the mirror, a hole is opened at the optical axis center part of themirror and the primary beam passes through this hole. A conductingmaterial or conductor is coated on the interior of the hole andconnected to a reference voltage part so that the interior of the holeis also maintained the same potential as a reference voltage.

In addition, two methods for the shape of photoelectron generation areexplained using FIG. 39. One method uses an FA aperture 2010 whichspecifies a beam system shape before being irradiated to a mirror withthe column. The beam shape is formed using the field aperture (FA) 2010,the beam is irradiated to the photoelectron surface and photoelectronshaving this shape are generated. At this time, the projection size ofthe field aperture (FA) 2010 is controlled by the lens location on theupper side of the field aperture (FA) 2010.

The other method is for coating a masking material of a pattern onto aphotoelectron surface. FIG. 40 shows an example which uses the anexample of coating a masking material of a pattern onto a photoelectronsurface in the primary optical system 2100 related to the secondembodiment of the primary optical system related to the presentinvention. As is shown in FIG. 40 a masking material 2122 is coated ontothe photoelectron surface 2122. This masking material 2122 has a patternshape hole and the hole part is not coated with the masking material.Due to the coating, photoelectrons are not generated from this part butfrom the part which is not coated with the masking material. That is,when DUV light is irradiated, pattern shaped photoelectrons aregenerated from the photoelectron surface part of the pattern shape whichis not masked. At this time, a material in which photoelectrons are notgenerated can be coated in advance as the masking material. Also, amaterial which a high work function, or a material with a low generationefficiency can be used. For example, carbon, Pt or Cr. However, aconducting material is used because potential non-uniformity is formedwhen charging up which brings bad effects such as curving of the orbitof emitting electrons.

FIG. 41 shows a method of reflecting light or laser which hastransmitted through and re-irradiating onto a photoelectron surface inorder to further improve efficiency. The light or laser which isirradiated from the photoelectron surface 2121 side is reflected withina light, laser transmittance part which includes a reflection surfacestructure (reflection surface 2123), returned to the photoelectronsurface 2121 and re-irradiated. Efficiency is improved since light or alaser is irradiated a plurality of times onto the photoelectron surface2021 in this method. For example, when the light or laser transmittanceof the photoelectron surface 2021 is 60%, an increase in the amount ofphotoelectrons generated corresponding to the number of times the lightor laser is irradiated is increased by re-irradiating the transmitted60% of the light or laser. A method of irradiating a plurality of timesis effective and not limited to this example. In particular, this levelof efficiency can be obtained by irradiating 2˜5 times. Irradiating morethan this can reduce the intensity of the light or laser and thereforeeffectiveness is significantly reduced. In this way, when irradiating aplurality of times is possible, the intensity of the irradiated light orlaser can expect to obtain the effect of ½˜⅕ the case of a singleirradiation. In particular, in the case where a large output lightsource is required, when there is not light source at all or in the casewhere operational management costs are high. At this time, since it ispossible to reduce costs, improve efficiency, reduce the effects of heatand the effects of element deterioration of a light introduction system,it is very effective to use a low output light source.

Furthermore, the examples explained in FIG. 40 and FIG. 41 are appliedto the primary optical system 2100 related to the second embodiment ofthe primary optical system related to the present invention. However,these examples are not limited to the embodiment and can be applied tothe primary optical system 2000 related to other embodiments.

Tenth Embodiment

Semiconductor Inspection Device having a double tube structure column Asdescribed above, the electron optical device 70 which is arranged withthe primary optical system 2100 shown in the second embodiment of theprimary optical system related to the present invention has differentsettings of voltage applied to each element from a general electron gun.That is, a reference potential V2 is set as a high voltage (as anexample, +40000V). Thus, the semiconductor inspection device 1 arrangedwith the electron optical device 70 related to the present inventionfirst has a double tube structure.

FIG. 42 shows an exemplary view of a double tube structure of asemiconductor inspection device related to one embodiment of the presentinvention. In FIG. 42, the first and second tubes are shown highlighted,however, the cross sections of the actual first and second tubes aredifferent to this. As is shown in FIG. 42, the electron optical device70 arranged with the primary optical system 2000 related to the presentinvention is comprised from two tubes, a first tube 10071 and a secondtube 10072 arranged on an exterior part of the first tube 10071, inother words, a double tube structure. In addition, a light source,primary optical system, secondary optical system and detector are housedon the interior of the dual tube structure. Also, a high voltage (as anexample, +40000V) is applied to the first tube 10017 and the second tube10072 is set to GND. A high potential space reference voltage V0 issecured at the first tube 10071 and keeps the second tube at GND. Inthis way, a GND connection of the device arrangement and electron shocksare prevented. The tube 10071 is fixed to the tube 10072 by insulationparts. The second tube 10072 is at GND and is attached to a main housing30. The primary optical system 2000, or the second optical system anddetector system 76 etc are arranged on the interior of the first tube10071.

The interval wall on the interior between the first tube 10071 and thesecond tube 10072 is formed with a non-magnetic part including a partsuch as a screw so that a magnetic field is not affected and so that amagnetic field does not affect an electron beam. Furthermore, althoughnot shown in FIG. 42, a side surface of the second tube 10072 isarranged with a space and a projecting part arranged with a part of thefirst primary optical system 2000 such as a light source andphotoelectron generation part is connected to the interior. Similarly, asimilar space to the space arranged in the second tube 10072 is alsoarranged in the first tube 10071, and the photoelectrons which aregenerated in the photoelectron generation part pass through this thesespaces and are irradiated to the sample. Furthermore, the light sourcedoes not always need to be arranged on the interior of the second tube10072, it can be arranged on the atmosphere side and introduced to thephotoelectron generation part housed within the second tube 10072 on thevacuum side. However, the first and second primary systems must behoused on the interior of the double tube structure. The detector may bearranged within the first tube 10071 or may be arranged at anindependent potential which is not related to the first and second tube.The potential of the detector surface of the detector is arbitrarily setand the energy of the electrons irradiated to the detector may becontrolled to an appropriate value. It is possible to operate thedetector by applying an arbitrary voltage as the detection sensorsurface potential of the detector in a state in which the potential isdivided by insulation parts with respect to the first and second tube.At this time, when the sensor surface potential is set at VD, the energyirradiated to the sensor surface is determined by VD-RTD. In the casewhere EB-CDD, or EB-TDI is used for detector, it is effective to use anirradiation energy at 1˜7 keV in order to reduce damage to the sensorand use the sensor for long periods of time.

Furthermore, another structure of the semiconductor inspection device 1arranged with the electron optical system 70 related to the presentinvention is explained below. FIG. 43 shows the entire structure of thesemiconductor inspection device 1 related to one embodiment of thepresent invention. As is shown in FIG. 43 the semiconductor inspectiondevice 1 related to one embodiment of the present invention includes asecond vacuum chamber 900. That is, a second vacuum chamber 900 isarranged in the semiconductor inspection device 1 and together witharranging a power supply source 910 for generating a high voltage withinthe second chamber 900, a lens column 71 in which the first tube andsecond tube are housed, and the second vacuum chamber 900 are connectedby a connection tube 920 and wires are arranged within the connectiontube 920. This is because in the electron optical device 70 related tothe present invention described above, a reference potential V0 is setto a high voltage unlike a conventional device. In order to set areference potential V0 to a high voltage, the semiconductor inspectiondevice 1 arranged with the electron optical device 70 related to thepresent invention is given a double tube structure. In addition, a highvoltage is applied to interior side first tube 10071. In the case wherea high voltage is applied, the vacuum feed through must be a large feedthrough in order to secure a creeping dielectric strength voltage on theatmosphere side which is low compared to a creeping dielectric strengthvoltage on the vacuum side. For example, an insulation part whichincludes an insulation creeping distance of 40 mm or more and a largeconnector with respect to insulation part is required at 40 kV with acreeping dielectric strength voltage of 1 kV/mm. The parts which arearranged in the lens column occupy a larger place and the column sizeand costs are significantly increased when there are many largeconnectors. Consequently, a power supply vacuum chamber is arranged inthe present invention. Since feed through from an output is not requiredby arranged a power supply vacuum chamber it is sufficient to simplyconnect wires to an electrode. At this time, since generated gas fromthe power supply can cause contamination, it is effective to insulatethe space between the power supply vacuum chamber and lens column usingan insulation part in order to cut a vacuum conduction at the middle ofa wire. In addition, the wire must be thick in the case of a highvoltage. In the semiconductor inspection device 1, when a sampleapplication voltage is set high is becomes necessary to arrange manythick wires on the periphery of a stage. When a wire with a largediameter is arranged on the interior of a working chamber a large torqueis required due to movement of a wire when a stage is operated, forexample, the force with which a wire rubs against a side surface becomeslarger which generates particles which is a problem. Therefore, a methodof setting the sample potential to GND and the reference voltage to ahigh voltage is very effective. At this time, it is even more effectiveto control the voltage of the detector surface and reduce sensor damage.The sample potential, the reference space potential and sensor surfacepotential are all set to different values. At this time, for example, itis very effective to set the sample potential to GND, the referencevoltage to 10˜50 kV and the sensor surface potential to 3˜7 kV. Inaddition, as described above, the power supply 910 is housed byarranging the second vacuum chamber 900, connected to a lens column etcby the connection tube 920 and a vacuum wire is realized by arrangedwires within the connection tube 920. A supply power (AC100V or DC24Vetc) is introduced from an external source to the power supply and anoptical communication method is used for communication. Connection fromthe atmosphere side is easy since a small feed through is sufficient atthis level of supply power.

In addition, as described above, because the invention includes a doubletube structure the interior side tube (tube 1) has a high vacuum andatmospheric pressure state is possible between the exterior side tube(tube 2) and the interior side tube (tube 1). At this time, it is notpractical to arrange an electrostatic electrode within the tube 1 sincethe number of wires connected by the tube 1 is large and the feedthrough of the vacuum/atmosphere is large. A lens, aligner and correctorwhich use a magnetic field are used for the lens, aligner and correctorat this time. In this way, it is no longer necessary to arrange a feedthrough on the tube 1 and it is effective in the case of forming a highvoltage reference space. Use of such a structure can be applied to thefirst to ninth embodiments previously described.

The semiconductor inspection device 1 arranged with the primary opticalsystem 2000 related to the present invention described above is providedby making each structure of the lens column, power supply second vacuumchamber and connection tube of the vacuum wire which connects the lenscolumn and second vacuum chamber described above a double structure.However, this is just an example and the semiconductor inspection device1 arranged with the primary optical system 2000 related to the presentinvention is not limited to this example. In addition, it is alsopossible to perform the embodiments described thus far, for example, theembodiments of the primary and secondary systems shown in the first toninth embodiments, using the double tube structure of the presentembodiment.

Eleventh Embodiment

A beam measurement method at a cross over location, and a primaryirradiation electron beam which uses this method, and a NA locationadjustment method and a semiconductor inspection device which uses thisadjustment method.

A semiconductor inspection method which uses an electron optical devicearranged with the primary electron system related to the presentinvention described above is explained below. Furthermore, the methodsdescribed below can be applied to a semiconductor inspection devicewhich uses an electron optical device arranged with a general electrongun.

In the embodiment, a projection-type observation device (an electronbeam observation device having a projection optical system) is used toobserve a sample. An electron beam observation device of this typecomprises a primary optical system and a secondary optical system. Theprimary optical system 2000 irradiates a sample with an electron beamemitted from a photoelectron generation part to generate electrons whichhave obtained information on the structure or the like of the sample.The secondary optical system has a detector, and generates an image ofthe electrons generated by the electron beam irradiation. Aprojection-type observation device uses an electron beam of a largediameter and provides an image over a wide area. That is, irradiation isperformed using an area beam not a spot beam such as general SEM.

When a sample is irradiated with an electron beam, electrons of aplurality of types are detected by the secondary optical system. Theelectrons of a plurality of types are mirror electrons, secondaryelectrons, reflected electrons, and backscattered electrons. In theembodiment, secondary electrons, reflected electrons and backscatteredelectrons are called secondary emission electrons. In addition, a sampleis observed by using mainly the characteristics of mirror electrons.Mirror electrons refer to electrons that do not collide with a samplebut bounce back immediately in front of the sample. The mirror electronphenomenon is caused by the effect of an electric field on the surfaceof a sample.

As described above, secondary electrons, reflected electrons, andbackscattered electrons are referred to as secondary emission electrons.The term secondary emission electron is also used when these three typesof electrons are mixed. Secondary electrons are typical among thesecondary emission electrons. Secondary electrons are thus sometimesdescribed as typical secondary emission electrons. Expressions such as“be emitted from a sample,” “be reflected from a sample,” and “begenerated by an electron beam irradiation” may be used for both mirrorelectrons and secondary emission electrons.

FIG. 44 shows a relation between the landing energy LE and gray level DNof a sample irradiated with an electron beam. The landing energy LE isenergy given to the electron beam with which the sample is irradiated.Suppose that an acceleration voltage Vacc is applied to an electron gunand a retarding voltage Vrtd is applied to the sample. In this case, thelanding energy LE is expressed by the difference between theacceleration voltage and the retarding voltage.

In FIG. 44, the gray level DN on the vertical axis represents thebrightness of an image generated from electrons detected by the detectorof the secondary optical system. That is, the gray level DN representsthe number of detected electrons. The more electrons are detected, thelarger the gray level DN becomes.

FIG. 44 shows a gray-level characteristic in an energy region of smallenergy near 0 [eV]. As illustrated, in a region in which LE is largerthan LEB (LEB<LE), the gray level DN stands at a relatively smallconstant value. In a region in which LE is LEB or less but not less thanLEA (LEA≦LE≦LEB), the gray level DN increases as LE decreases. In aregion in which LE is less than LEA (LE<LEA), the gray level DN standsat a relatively large constant value.

The above-described gray-level characteristic is related to the type ofelectrons to be detected. In the region LEB<LE, almost all electrons tobe detected are secondary emission electrons. This region can bereferred to as the secondary emission electron region. On the otherhand, in the region LE<LEA, almost all electrons to be detected aremirror electrons. This region can be referred to as the mirror electronregion. As illustrated, the gray level in the mirror electron region islarger than that in the secondary emission electron region. This isbecause the distribution area of mirror electrons is smaller than thatof secondary emission electrons. Since the distribution area is small,more electrons can reach the detector and the gray level increases.

In addition, the region LEA≦LE≦LEB is a transition region from thesecondary emission electron region to the mirror electron region (orvice versa). This region is a region in which mirror electrons andsecondary emission electrons are mixed, and can also be referred to asthe mixture region. In the transition region (mixture region), the yieldof mirror electrons increases and the gray level increases as LEdecreases.

LEA and LEB denote minimum and maximum landing energy of the transitionregion. Specific values of LEA and LEB will be described. Study resultsof the inventors show that LEA is −5 [eV] or more and LEB is 5 [eV] orless (that is, −5 [eV]≦LEA≦LEB≦5 [eV]).

The merits of the transition region are as follows. In the mirrorelectron region (LE LEA), all electrons generated by the beamirradiation become mirror electrons. For this reason, all detectedelectrons would be mirror electrons regardless of the shape of thesample; the difference in gray level both at hollows and at bumps of thesample would be small; and the S/N ratio and contrast of patterns anddefects would be small. It is therefore sometimes difficult to use themirror electron region for inspection. In the transition region, on theother hand, mirror electrons are characteristically and specificallygenerated at edge-shaped parts, and secondary emission electrons aregenerated at the other parts. The S/N ratio and contrast of edges cantherefore be increased. The transition region is thus very effective forinspection. This will be described in detail below.

FIG. 45 shows the above-described phenomenon in the transition region.In FIG. 45, all electrons become mirror electrons without colliding withthe sample in the mirror electron region (LE<LEA). In the transitionregion, on the other hand, some electrons collide with the sample, whichemits secondary electrons. The ratio of the secondary electors becomeshigh as LE becomes larger. Though not shown in the figure, onlysecondary electrons are detected if LE exceeds LEB.

In the present invention, is a method of creating and adjustingconditions of an electron beam of a secondary optical system for formingan irradiation electron beam and image, including secondary emissionelectron region, a transition region and mirror electron region, andalso including a pattern having an uneven structure and a pattern withno asperities. The present invention can achieve dramatic efficiency,high accuracy adjustment and condition creation which are describedbelow.

The present invention has a significant feature of measuring thelocation and formation of a beam at a cross over location (belowreferred to as CO location) at a midpoint of the secondary opticalsystem. Conventionally, an NA was moved, and image taken and thecontrast of the image was evaluated without measuring the beam at a COlocation. This took a considerable amount of time. The conventionalsequence is as follows.

-   a) Form image forming conditions at a lens between the CO location    and detector.-   b) Use a large diameter in the case where an NA is present.    Alternatively, remove the NA. It is preferable to be able to observe    the entire CO. For example, φ1000˜˜5000 μm.-   c) Image a beam of the CO location.

In the present invention, the structure of the apparatus are describedherein in order to efficiently perform this type of imaging andadjustment and improve deterioration due to contamination andreplacement and maintenance, however, characteristically, a movable typenumerical aperture (NA) 10008 is arranged. In this way, a measurementexample of a beam shape at a CO location with respect to LE is shown inFIG. 46. FIG. 46 shows a measurement example of a beam shape at a COlocation with respect to LE. In FIG. 46 shows formation of a beamarriving at a CO location on the upper stage and phenomena in a mirrorregion, transition region and secondary emission electron region of abeam irradiated to a sample surface on the lower stage. In addition, inthe upper stage, mirror electrons are shown by black dots and thesecondary emission electrons are shown by circles. Only the mirrorelectrons are observed with respect to LE in the mirror electron region.The mirror electrons and secondary emission electrons are observed inthe transition region. Only the secondary emission electrons areobserved in the secondary emission electron region, and the mirrorelectrons are not observed. The location, size, intensity of the mirrorelectrons and size and intensity of the secondary emission electrons aremeasured using image data obtained from this imaging.

In addition, with this observation it is possible to rapidly determinewhich state among three states the sample is in when an irradiationelectron beam is made to impact the subject sample. Conventionally, avague prediction was performed from the irradiation conditions and theobtained image. An accurate determination of the state could not bemade. In addition, errors due to power supply setting accuracy and theeffects of optical axis conditions also could not be determined. Thiswas because formation of a mirror electron region, transition region issensitive to optical axis conditions and apparatus for controlling thiswould be affected by condition errors. For example, the setting accuracyof a power supply is generally has an accuracy of 0.1%. Setting errorsof a 5000V setting power supply would become 5V. When a variation of 5Voccurs, a transition region would often become a mirror region and atransition region would often become a secondary emission electronregion. Since this could not be confirmed, only a vague predictionstating a region might be a mirror electron region or a transitionregion due to setting values could be made.

Furthermore, in the present invention, a setting method of an NAlocation for adjustment of a primary irradiation electron beam and imageformation is described using a method for performing this measurement.It is assumed that the direction of a sample such as a mask or wafer andcoordinates of a secondary optical system (column) and locationadjustment have been performed.

FIG. 47 shows an irradiation angle of a primary beam to a sample in aninspection method related to one embodiment of the present invention. Asis shown in FIG. 47, an irradiation angle of an irradiation electronbeam is given as θ and an irradiation direction with respect to a sample(or column coordinates) is given as α. That is, and angle from aperpendicular direction (Z direction, same as the optical axis directionof a secondary optical system) with respect to a sample surface is givenas θ. For example, when θ=0, the sample surface is irradiation from aperpendicular direction. When θ=90°, the sample surface is irradiatedfrom a horizontal direction. When θ=45°, which is an oblique direction,the sample surface is irradiation from an angle of 45°. In addition, θmay be displayed as an absolute value from the Z axis. θ has the samevalue if it has the same angle on the right side or on the left sidewith respect to the Z axis. Usually, θ is used within a range of 0˜45°.As an example of a in the sample (or column coordinates) X, Y directionsare given as Y direction for the E direction in ExB and the B directionis given as X direction. For example, an E+ side of ExB (direction inwhich a primary optical system exists) is given as Y+ and the E− side isgiven as Y−. At this time, a right 90° angle direction with respect toY+ becomes X+ when the sample is seen from the detector side, and X−becomes a left 90° angle direction. In addition, for example, when asample includes a pattern region with vertical line/space (L/S) and ahorizontal line/space (L/S), the sample is arranged so that the verticalline becomes a Y direction and the horizontal line becomes the Xdirection. At this time, for example as is shown in FIG. 47 (a), it ispossible to determine the sample irradiation angle in which the X+direction is assume to be 0° as α. When α=0°, the irradiation angle of aprimary electron beam becomes the X+ direction. When α=45° which oneexample of an oblique direction, the irradiation angle becomes anoblique 45° angle in an intermediate direction between X+, Y+. It isalso possible to form the same irradiation direction of a primaryelectron beam with respect to a vertical L/S and horizontal L/S. Whenthe values of θ and α mentioned above are adjusted, an observation ismade of the beam at the CO location when an NA aperture of the secondaryoptical system is present as in FIG. 48. FIG. 48 shows an example of aCO location beam observation and is an adjustment example in atransition region.

A secondary emission electron beam becomes circular at a CO location.Since these are emission electrons from the surface when the electronbeam collides with a sample, the emission direction from the surfacebecomes isotropic and therefore circular at the CO location. However,because mirror electrons are reflected in the vicinity of a surface inthe direction affected by θ and α mentioned above, mirror electrons areformed at a location which reflects θ and α.

For example, when the irradiation angle to a sample is α, a mirrorlocation is formed at the angle direction of α at the CO location withrespect to the circular shape of secondary emission electrons. Inaddition, a perpendicular direction of the sample surface is given as Z,the detector direction is given as Z+ and an irradiation angle withrespect to Z is given as θ. The mirror location of CO location isaffected depending on the size of θ. That is, as is shown in FIG. 48,when θ (absolute value) is large, the distance LM from the center of COof the secondary emission electrons becomes larger. That is, in the caseof oblique irradiation, when the irradiation θ is large, the mirrorelectrons location us formed at location away from the CO center of thesecondary emission electrons. In addition, when a primary electron beamis irradiated at a perpendicular angle, a mirror location is formed atthe CO center location of the secondary emission electrons.

This example is described in FIG. 49. FIG. 49 shows a mirror locationaccording to the irradiation angle of a primary electron beam. In thecase of an electron beam irradiated in the X direction, the mirrorelectron location is formed on the X axis with respect to the CO of thesecondary emission electrons. In the case of an electron beam irradiatedin the Y direction, the mirror electron location is formed on the Y axiswith respect to the CO of the secondary emission electrons. In the caseof irradiation from an oblique angle α, a mirror electron location isformed in the α direction with respect to the CO of the secondaryemission electrons. Often used α are 0°, 30°, 45°, 60°, 90°, 120°, 150°,180°, 210°, 240° and 270°. In addition, θ is often used in the range of0˜45°. Also, in a sample which has an uneven structure surface in whichhigh contrast and S/N are obtained, for example, an EUV mask, nano-printmask or semiconductor wafer, θ is often used in the range of 0˜20°.

It is possible to control an irradiation angle of this primary systemusing the primary system beam aligner. In addition, it is also possibleto perform an adjustment using a primary system beam aligner as the Xdirection and EXB as the Y direction. Also, a beam aligner may also beused instead of EXB in the Y direction.

In the present embodiment, an NA adjustment is performed is order toform electron image conditions with a high contrast and S/N. This isbecause the image data obtained is different due to the relationshipbetween a mirror electron location and NA location and image qualityvaries significantly. For example:

-   a) An image including many mirror electrons: arrange an NA in the    vicinity of a mirror electron location-   b) An white hollow/black bump image with many mirror electrons in    the hollow parts in the case of a uneven structure pattern-   c) An black hollow/white bump image with few mirror electrons in the    hollow parts in the case of a uneven structure pattern-   d) An image, vertical/horizontal pattern etc with an asymmetric    contrast-   e) An image etc formed with mirror electrons on the edge part of    asperities

Consequently, in order to obtain a demanded image it is necessary tocalculate and set the relationship between a mirror location and NAlocation. Conventionally, because understanding of the phenomena thatoccurred was insufficient and an adjustment method as not understood,conditions was determined by blindly moving the NA and obtaining animage. Using the present invention, it is possible to improve workefficiency and significantly reduce time and costs. An NA movablemechanism is required in order to adjust and set the NA location. Inaddition, it is more preferable if this is a two dimensional movingmechanism. This is because in a one dimensional moving mechanism, whenan MC (mirror electron location) is in an oblique direction or axialdirection which from which it can not be moved (for example, can notmove in a y direction when it can only be moved in an x direction) withrespect to the CO center of a secondary emission electron, an NA can notbe arranged between the center locations of an MC and CO.

FIG. 50 and FIG. 51 show examples of a mirror electron location and NAlocation. The same condition adjustment method may be applied also to aplanar surface sample as well as a sample having an uneven structurepattern. In the case where it is desired to form an image which takesinto account changes in the potential or changes in the material of aplanar sample, it is possible to calculate and create conditions foreasy removal of such changes using the present invention. For example,the present invention can be applied in the detection of small foreignmaterials, the remains of cleaning, contamination etc or to detection ina mixed pattern of a conductive material and insulation material. Inthis case it is also possible as stated above to use a conditioncreation method in order to calculate conditions of defects or a patternwith a high contrast and S/N. In addition, it is also possible torealize highly sensitive detection which was not conventionallypossible. By being able to perform this type of adjustment it wasconfirmed that a contrast of ×1.2˜2, S/N×1.5˜5 can be obtained comparedto a method performed while looking an image which is very effective foradjustment time Tc and reproducibility, for example, Tc=½˜ 1/10 can beobtained compared to conventional examples.

There are two categories of an NA setting location, arranging on theperiphery of a mirror electron location and arranging the NA in alocation away from the mirror electron location. The effects of a mirrorelectron decrease the further away the NA location is set.

An example of image formation is shown below.

1) Hollow White Part/Bump Black Part Signal Image in an Uneven Pattern

An example where high contrast, high S/N is obtained by an increase inthe amount of electrons where localized mirror formation occurs.

FIG. 52 shows a relation between the landing energy LE and the graylevel DN at an edge part of an uneven structure on a sample surface. Theedge part refers to a part which is located at both edges of a hollowand in which the height of the sample changes. In FIG. 52, the dottedline represents the gray-level characteristic of the edge part, and thesolid line represents that of the other part. The characteristic of theother part corresponds to that in FIG. 44.

As shown in FIG. 52, the characteristic line is different between theedge part and the other part. The characteristic line of the edge partis shifted in a direction in which the landing energy increases. Thatis, at the edge part, the upper and lower limits of the transitionregion are large, and the upper limit of the transition region is LEB+5[eV], where LEB is the upper limit of the transition region for the partother than the edge part. Such a shift in the characteristic line occursbecause the shape, structure, material, or the like is different betweenthe edge part and the other part. The shift in the characteristic linecauses a gray-level difference ΔDN between the edge part and the otherpart.

The reason why the characteristic of the edge part is different fromthat of the other part as shown in FIG. 52 and the reason why thegray-level difference ΔDN occurs will next be discussed.

FIG. 53 is an example of the uneven structure of a sample, showing across section of a fine line/space shape. For example, the bump is aline and the hollow is a space. The line width and the space width are100 μm or less. In the shape in FIG. 53 (a), a conductor (Si) has theuneven structure. An oxide film (SiO₂ or the like) is formed on top ofthe bumps. Similarly, in the shape in FIG. 53 (b), TaBO is formed on thetop of the bumps.

FIG. 54 shows a phenomenon in which mirror electrons are generated atthe edge part of the uneven structure when the structure in FIG. 53 (a)is irradiated with an electron beam. A vertically-striped pattern isformed in FIG. 54. When irradiation is made with an electron beam,irradiation electrons change their path near one edge of a hollow(groove), turn sideways, and move toward the opposite edge of thegroove. The irradiation electrons then change their path again near theopposite edge and return upward. Irradiation electrons thus becomemirror electrons without colliding with the sample. The mirror electronsgenerated at edges in this way can be referred to as edge mirrorelectrons. Edge mirror electrons are generated symmetrically from bothedges. FIG. 55, like FIG. 54, also shows edge mirror electrons generatedin the structure in FIG. 53 (a). A horizontally-striped pattern isformed in FIG. 55. At this time, because this takes place in atransition region, electrons other than edge mirror generation partcollide with the surface and secondary emission electrons are generated.As a result, for example, a pattern contrast and S/N are determined bymirror electrons at the edge part and secondary emission electrons atother parts. Because the transmittance of the mirror electrons is high,it is possible to obtain a high contrast and S/N. In addition, sometimesan image can not be formed by completely resolving an edge mirrordepending on a pattern shape and capabilities of a secondary opticalsystem. For example, because the reduction of secondary optical systemaberration is insufficient, edge mirror electrons are observed as oneunit. Consequently, observation is sometimes made by a white signalwhere a space part is an edge mirror and a black signal where a linepart is a secondary emission electron. In addition, depending on theirradiation direction of a primary electron beam, edge mirrors aresometimes generated only in a one direction of an edge part. At thistime, observation is sometimes made by a white signal where a space isan edge mirror and a black signal where a line part is a secondaryemission electron.

In addition, FIG. 56 is another example of the electron path along whichthe irradiation electrons change into edge mirror electrons. In thisexample, the irradiation electrons enter toward one edge of a hollow, goinside the hollow along a curved path near the one edge, turn aroundwithout colliding with the bottom of the hollow, and go near the otheredge of the hollow to become mirror electrons. Such mirror electrons arealso edge mirror electrons. In the edge structure, each irradiationelectron is considered to go through the path in FIG. 54 or 56, or gothrough a path intermediate between the paths in FIGS. 54 and 56, tobecome an edge mirror electron.

The reason why the path of electrons easily bends near an edge will nextbe described. In the structure in FIG. 53, the oxide film is formed onthe surface of the bumps of the conductor. In this structure, the oxidefilm on the sample surface is negatively charged. The potential of theconductor within the hollow is relatively higher than that of the oxidefilm. Since the potential changes near an edge, the path of electronseasily bends as described above, and consequently edge mirror electronsare generated.

Precharge is also preferable in the embodiment. Precharge is electronbeam irradiation to be made before sample observation. An insulatingarea on a sample is negatively charged by precharge (the oxide film onthe sample surface is negatively charged in the example in FIG. 54 andthe like). Precharge stabilizes the potential of the insulating area.Consequently, edge mirror electrons are stably generated, and thecharacteristic in FIG. 52 is stably obtained. Sample observation canthus be satisfactorily carried out, and the precision of inspectionusing the sample observation result can also be improved.

Irradiation with the electron beam for precharge may be made by usingthe electron optical system for sample observation. Alternatively,another electron gun may be provided for precharge.

FIG. 57 shows another example related to the uneven structure of asample. FIG. 57 is also a cross section of a line/space shape. In FIG.57, a bump of an oxide film (SiO₂ or the like) is formed on a Sisurface. In such structure, an equipotential surface bends at both edgesof a hollow. The path of irradiation electrons bends due to the bend ofthe equipotential surface. As a result, irradiation electrons go throughthe paths shown in FIGS. 54 to 56 to become edge mirror electrons alsoin the structure in FIG. 57. Precharge is also suitably performed in thestructure in FIG. 57, thereby allowing the potential of the oxide filmon the bump to be stabilized.

Sometimes the uneven structure is formed only of a conductive material.In this case also, an equipotential surface is formed along the bumpsand hollows. The equipotential surface bends at both edges of a hollow.The path of irradiation electrons bends due to the bend of theequipotential surface. As a result, irradiation electrons go through theabove-described paths to become edge mirror electrons. In addition, inthe structure in FIG. 53 (b) the same can be considered with respect toa structure mask which does not include TaBO. This may also be a EUVmask.

There is a natural oxide film on the surface of the conductive film alsowhen the uneven surface is formed only of a conductive material.Precharge is therefore preferable and can stabilize the potential.

As described in detail above, electrons at a hollow of a sample go nearboth edges and turn around to become edge mirror electrons. Edge mirrorelectrons are therefore more easily generated than mirror electronsgenerated by a normal part. As a result, the transition region for theedge part, compared to that for the part other than the edge part,extends more in a direction in which the energy increases, as shown inFIG. 52.

In addition, mirror electrons and secondary emission electrons are mixedin the above-mentioned region. Secondary emission electrons aresecondary electrons, reflected electrons, or backscattered electrons (ora mixture thereof), as described before. Secondary emission electronsare emitted in an isotropically-spread manner. For this reason, at mostonly several percent of the electrons reach the detector. On the otherhand, edge mirror electrons are generated by irradiation electrons beingreflected as-is. The transmittance (the rate of reaching the detector)of edge mirror electrons is therefore almost 100%. Consequently, a highbrightness (gray level) is obtained, and the gray-level difference ΔDNwith the surroundings increases.

At the edge part, as described above, mirror electrons are easilygenerated and the transmittance of mirror electrons is high.Consequently, as shown in FIG. 52, the gray-level characteristic line ofthe edge part is shifted in a direction in which the landing energy LEincreases, and a gray-level difference ΔDN occurs between the edge partand the other part.

Using the above-described phenomenon, the embodiment generates ahigh-resolution and high-contrast pattern image. The hollow structuredescribed above corresponds to the hollow pattern of the invention. Inthe embodiment, the landing energy is set so that edge mirror electronsare efficiently generated at the hollow pattern. The landing energy LEwill be set to a very low value as compared to conventional commonobservation techniques, as illustrated. Such an energy setting increasesthe gray-level difference ΔDN between a pattern and the surroundings,allowing a high-resolution and high-contrast image to be obtained.

Specifically, the landing energy LE is set so that LEA≦LE≦LEB orLEA≦LE≦LEB+5 [eV] is achieved. This allows the landing energy LE to beset in a region in which mirror electrons and secondary electrons aremixed.

As described before, study results of the invention show −5[eV]≦LEA≦LEB≦5 [eV]. For example, suppose that LEA=−5 [eV] and LEB=5[eV]. In this case, the landing energy LE is set as −5 [eV]≦LE≦5+5[eV]=10 [eV]. More specifically, the state of mixture of mirrorelectrons and secondary emission electrons varies depending on thelanding energy LE, and the gray-level difference also varies. A greatadvantage may be obtained by setting the landing energy LE in a regionin which the yield of mirror electrons is relatively small.

2) Hollow Black Part/Bump White Part Signal Image in an Uneven Pattern

An example where high contrast, high S/N is obtained by a black signaldue to a mirror not reaching a detector where localized mirror formationoccurs.

Mirror electrons which are formed at a hollow part collide into a sidewall etc. Alternatively, their trajectory is misaligned and because theydo not reach the upper CO location or detector location, the hollow partsignal is reduced and detected as a black signal.

At this time, in FIG. 52 the signal characteristics of a hollow part areb and other parts are c. The signal of a bump part is obtained by mirrorelectrons, mirror electrons+secondary emission electrons or secondaryemission electrons reaching the detector. At this time, when hollow partmirror electrons collide with a side wall surface, secondary emissionelectrons are generated from the side wall material. In addition, thebump part mirror electrons form an image as a white signal due to thelarge amount of electrons arriving at the detector. At this time,secondary emission electrons form a black signal. It is possible toobtain an uneven pattern, that is, conditions of a high contrast and S/Nof a line/space structure using this hollow black signal and bump partwhite signal, and a defect inspection with a level of sensitivity ispossible. In addition, electrons from the bump part, are sometimesincluded mirror electrons and secondary emission electrons generated bycolliding one part of a primary electron bean into a sample surface. Atthis time also, because the amount of electrons arriving at the electrondetector from the bump part is large, it is possible to obtain an unevenpattern, that is, conditions of a high contrast and S/N of a line/spacestructure using this hollow black signal and bump part white signal, anda defect inspection with a level of sensitivity is possible. At thistime, effects are received from the material of the outermost layer.There are sometimes more secondary emission electrons in an oxide filmof SiO2 or TaBO than a side wall material. At this time, it is possibleto obtain an even higher contrast and S/N. In addition, the trajectoryof the mirror electrons formed at the hollow parts is greatlymisaligned, or misaligned from a location whereby they can not passthrough the NA, or many collide with a side wall. At this time, theelectrons from the hollow part change into secondary emission electronswhen a part of a primary beam irradiated to the hollow part collide withthe side wall, and become a black signal due to the low amount ofsecondary emission electrons. However, because the entire primary beamwhich is irradiated to a bump part and generates mirror electrons, a mixof mirror electrons and secondary emission electrons or secondaryemission electrons from a bump part has an effect on the formation ofthe image, therefore it is possible to obtain a relatively larger amountof bump electrons than the hollow part and thereby obtain a highcontrast and S/N.

In this case also, the relationship between the irradiation angle θ of afirst irradiation electron beam and α, and the relative relationshipbetween the mirror location of a secondary optical system and the NAlocation has a significant effect on the formation of the image. It isalso possible to cut the hollow part mirror electrons using theconditions of the NA location. Such adjustment is performed and theconditions which can obtain a high contrast and S/N of an uneven patternare measured and set.

(Beam Measurement Mechanism at a CO Location: Second Detector)

It is possible to create conditions and adjust high accuracy of anelectron beam with respect to various patterns by measuring the locationand formation of a beam at a CO location. It is effective to arrange amovable numerical aperture for performing this type of adjustment. Inparticular, an aperture movable in a biaxial (x, y directions) directionis required. In addition, because the CO location sometimes changes in az direction due to lens conditions, an aperture movable in an x, y, ztri-axial direction is more preferable.

However, even if a movable type numerical aperture is arranged, only onedetector is used each time adjustment is performed. An electron imagefrom a mask or wafer, which is formed into an image by the secondaryoptical system, is primarily amplified in the micro-channel plate (MCP)of a detector and then impinges against a fluorescent screen to beconverted into an optical image. The image that has been converted intothe light by the detector is projected on the TDI-CCD by the FOP systemdisposed in the atmosphere through a vacuum permeable window on aone-to-one basis. When a detector is frequently used whenever adjustmentis performed, damage to the micro channel plate (MCP) etc becomes worse,and frequent replacement of the detector is required. Because a stillimage is used for optical axis adjustment of a secondary optical systemor for adjusting an electron image, an electron intensity distributionwithin the still image is maintained for a long time. In other words,imaging is performed in a state where whereby a part with many electronsand a part with few electrons are maintained for more than a fixedperiod of time. At this time, because element deterioration is differentfor parts with many electrons and parts with few electrons, a localizedgain differential occurs which produces variations in gain in thedetector itself. This causes an increase in the amount of artificialdefects when the next stage inspection is performed and deterioratesdetection capabilities. Consequently, it is preferable to includeanother detector when imaging a still image. At the time of aninspection, because imaging is performed while continuously changingparts having different obtained electron distributions during a shortperiod of time while moving a stage, there is little deterioration of adetector due to variations is gain.

A second detector is arranged immediately anterior to the inspectiondetector as a means of measuring the location and formation of a beam ata CO location where frequent replacement of this type of detector is notrequired and an optical adjustment and as a detector for measuring abeam at a CO location. FIG. 58 shows the principle of the seconddetector related to the present invention. FIG. 58 (a) shows a secondaryoptical system of the present invention, and FIG. 58 (b) shows anelectron beam of secondary emission electrons or mirror electrons at anumerical aperture (NA) 10008 location, passing through a lens andforming an image at a detector 76-2. The second detector 76-2 related toone embodiment of the present invention is arranged between thenumerical aperture 10008 and detector 76 shown in FIG. 58 (b), themovable type numerical aperture (NA) 10008 is moved thereby imaging ofthe location and formation of a beam of the CO location at the seconddetector is performed. Here, it is sufficient that it is possible totake a still image of the formation and location of a beam of the COlocation (or NA location). Adjustment is repeatedly performed based onthe data imaged by the second detector 76-2 and an inspection isperformed after adjustment.

The secondary emission electrons or mirror electrons form an image onthe sensor surface of the detector via the numerical aperture (NA)10008. This two dimensional electron image is obtained by the seconddetector 76-2, converted to an electric image and sent to an imageprocessing unit. A transfer lens or magnification projectionelectrostatic lens may be used between the numerical aperture 10008 andthe second detector 76-2 so that an electron beam image of the COlocation can be imaged by the second detector 76-2.

It is possible to use an EB-CCD or C-MOS type EB-CCD as the seconddetector 76-2. A pixel size may be ½ to ⅓ of the pixel size of an EB-TDIwhich is the first detector (detector 761). In this way, imaging with asmaller Px size than the first detector is possible. Px size is a valuewhereby a pixel size is divided by optical magnification, and the sizeof image partitions on a sample surface. For example, Px size=10 um/1000magnification=10 nm when each side of the pixel size is 10 μm andmagnification is 1000 times. Using a second detector which has a smallerpixel size than the first detector it is possible to perform a surfaceobservation with a smaller Px size than the first detector. The EB-TDIof the first detector, and the EB-CCD or C-MOS type EB-CCD of the seconddetector do not require a photoelectric conversion mechanism and a lighttransmission mechanism. Electrons directly enter the sensor surface ofan EB-TDI. Consequently, the resolution does not deteriorate, so that ahigh MTF (modulation transfer function) and high contrast can beobtained. The C-MOS type EB-CDD can significantly reduce backgroundnoise compared to a conventional EB-CDD and therefore is very effectivefor noise reduction caused by a detector, and it is possible to improvecontrast and S/N compared to a conventional example when performingimaging using the same conditions. In particular, it is effective whenthe number of obtained electrons is small. It is about ⅓˜ 1/20 moreeffective in noise reduction than a conventional type EB-CCD.

A beam which passes through the numerical aperture (NA) 10008 and formsan image at the detector surface is detected by the second detector76-2, condition creation of the electron beam and the location of thenumerical aperture (NA) 10008 are adjusted using the location andformation of the detected beam. A sample is inspected using thedetection system 76 after performing various adjustments using thedetection results of the second detector 76-2. Therefore, because thedetection system 76 is used only when performing an inspection, it ispossible to control the frequency of replacing the detection system 76.In addition, because the second detector 76-2 only images a still image,there is no influence on an inspection even if deterioration occurs. Inorder to achieve this type of image forming conditions, for example,conditions for forming an electron image in the first detector,conditions for forming an image in the second detector, conditions forforming a beam an image in the second detector using the shape of a beamwhich arrives at a CO location for observing a beam at a CO locationetc, referring to the example in FIG. 33 (a), the lens intensity of thetransfer lens 10009 is adjusted and certain image formation conditionsare used by measuring the optimum conditions for the first detector andsecond detector. In addition, a lens 741 may be used instead of thetransfer lens 10009. Because the distance between the center of a lensand a detector changes, the magnification changes between using thetransfer lens 10009 and the lens 741, therefore, a suitable lens andmagnification should be selected.

It is effective to use the second detector 76-2 described above togetherwith an adjustment method related to the present invention forperforming measurement of the location and shape of a beam at the COlocation described above, conditions creation of an electron beam andadjustment of high accuracy. In addition, the second detector 76-2 mayalso be applied to an electron optical device arranged with the generalelectron gun as well as an electron optical device arranged with the newelectron generation part related to the present invention. The presentembodiment can also be applied to the devices described in the first toeleventh embodiments described above. An electron beam was used as anexample of a primary beam in the example of a beam, NA locationadjustment method described above, however, an irradiation system canalso be applied in the case of light or a laser. It can also be appliedwhen a laser or light is irradiated to generate electrons from a samplesurface and appropriately setting a cross over size of these electronsor a relationship between a center location and NA setting location. Inthis way, electron image formation with a good level of resolution ispossible.

In addition, as another example, it is also possible to include a thirddetector which can move with the NA in an x, y direction as is shown inFIG. 58 (c), at an NA location. For example, a third detector 76-3 maybearranged as set as one unit to a setting plate of the NA. At this time,it is possible to move the plate for observing the shape and location ofa beam which arrives at the NA location, move to coordinates where thecenter of the third detector 76-3 arrives at the optical axis center,and directly observe the arriving beam using the third detector 76-3. Inthis way, it is no longer necessary to perform adjustment of subsequentlenses.

Twelfth Embodiment

Inspection device arranged with an optical microscope and SEM in thesame chamber

Furthermore, observation using a SEM is sometimes necessary whenperforming an inspection of a sample using the above described detector.Thus it is very effective to arrange a projection type opticalinspection device and a SEM within the same chamber (refer to FIG. 59).For example, in an inspection of a fine pattern such as a EUV mask orNIL (nanoprint lithography) mask, inspection of an ultrafine patternwith a high level of sensitivity using imaging conditions of aprojection type optical pattern and a pattern defect is demanded. In thecase where a projection type optical inspection device and a SEM arearranged within the same chamber, it is possible to load a sample ontothe same stage and perform observation and an inspection of the sampleusing both a projection optical method and a SEM. The usage method andits merits are as follows.

First, because a sample is loaded onto the same stage, a coordinaterelationship is unambiguously measured when moving the sample betweenthe projection type and the SEM thereby it is possible to easily specifythe same parts with a high level of accuracy. When a sample is movedbetween separated devices, it is necessary to align each of the samplesrespectively for arranging on different stages, and thus separatelyperformed alignment of the sample would cause a location error of 5 to10 μm for one and the same position. Due to this type of locationmisalignment, a place which is misaligned with a defect spot isreviewed, and a place with no defects is mistakenly imaged, andmistakenly judged to have no defects. In particular, in the case of asample with no pattern, a location reference can not be specified andtherefore such error becomes even larger, about 2˜10 times compared to asample having a pattern.

Secondly, a sample is arranged on the same stage and the same chamber,the same position can be precisely located even if the stage movesbetween the projection type the SEM, therefore, a location can bespecified with a high level of accuracy, for example, it is possible tomove a location of a foreign material or defect within a range of 0.05˜1μm with an accuracy 1 μm or less. In this way, it is effective when theinspection of the sample is first performed by the projection method toinspect a pattern and pattern defect. After that, location and detailedobservation (reviewing) of the detected defect is performed by the SEM.Since the position can be located accurately, not only the presence orabsence of a defect (false detection if absent) can be determined, butalso detailed observation of the size and shape of the defect can beperformed quickly. The separate installation of a device wastes aconsiderable amount of time for detecting and specifying a patterndefect.

In the embodiment, as described above, an ultrafine pattern can beinspected with high sensitivity by using conditions for imaging apattern and with the projection-type optical method. In addition, theprojection-type optical method and the SEM-type inspection device aremounted in the same chamber. Consequently, in particular, inspection ofan ultrafine pattern of 100 nm or less and determination andclassification of a pattern can be carried out with great efficiency andspeed. Examples are described in detail below.

Example 1

The invention includes the following functions and apparatus when theoptical microscope, projection type optical system and SEM explainedabove are arranged within one chamber.

The optical system center of the optical microscope, projection typeoptical system and SEM are each calculated in advance, the coordinaterelationship of the these centers are stored in a memory etc, and it isimportant to be able to move these stored optical system centercoordinates. An apparatus for achieving this may be installed in thepresent example. When the same spot is observed with respect to a sampleloaded on the same stage with the same chamber, it is possible to easilymove between the stored optical centers using a button or clickoperation on a PC control screen. Because the sample is arranged on thesame stage, it is possible to move or stop the location of the samplewith a high level of accuracy, for example, 0.05˜0.1 μm. In addition, ifcontrol is improved when the sample is stationary, a level of accuracyof 0.05˜0.1 μm is possible. As an example of this control, stopping asample using a plurality of stop allowable values can be given, forexample, using two types of allowable values such as A≦1 μm or B≦0.1 μm.In this way, it is possible to stop a sample smoothly and efficientlyusing a plurality of allowable values and using small allowable valuesstep by step.

(Alignment Sequence)

The relationship between sample alignment in each optical system, thatis, optical microscope, projection type optical system and SEM, sensoralignment in a detector in a projection type optical system and imageformation alignment is required for making the above described operationpossible. Depending on how these are measured, the capabilities ofoperation processes, required time and location accuracy, falsedetermination and categorization of defect types are affected. In thepresent case, the following sequence is performed in order to obtainefficiency and accuracy.

a) Determining a Sample Alignment Using an Optical Microscope (Refer toFIG. 60)

This involves matching the movement direction of a stage and thedirection of a sample and determining the direction of the sample. Forexample, the sample is rotated using a rotation stage etc, and arotation angle θs of the sample is determined so that the y direction ofthe sample is matched with the movement direction (y direction) of thestage. For example, in the case where there are 2 or more representativepattern marks in the y direction of the sample, 2 patterns or marksseparated in the y direction by 10˜300 mm are used. At this time, therotation angle Os of the sample is measured and determined so that thesetwo patterns or marks arrive on the optical center of the opticalmicroscope. At this time, it is possible to obtain an alignment accuracyof 1/10˜ 1/100 Px by performing image processing such as patternmatching.

b) Determining a Rotation Angle θt of a Detector which Detects anElectron Image of a Projection Type Optical System.

This angle adjusts and determines the rotation angle θt for matching they direction (direction in which each pixel lines up in a y direction) ofa TDI sensor (time delay integration CCD-TDI sensor) or CCD sensor withthe movement direction of a stage. Specifically, the following operationis performed. Patterns or marks separated by a distance of around 10˜300mm are used. The stage movement direction and rotation angle θs of thesample are adjusted using a) described above, and the stage movementdirection y and y direction of the sample are adjusted at a high levelof accuracy, for example, adjusted to within 1/1000˜ 1/100000 rad, orwithin 1/10000˜ 1/100000 rad. In this state, the stage is moved in a ydirection and an image is simultaneously obtained, and the rotationangle θt where resolution of a TDI image of a pattern or mark is atmaximum, for example, where contrast is at its maximum, is calculated. Aone dimensional L.S pattern etch in a Y direction may be used as thepattern. The L/S pattern becomes distorted and contrast decreases whenthe rotation angle θt is misaligned. Contrast increases when therotation angle θt is an appropriate value, and the most optimum valuecan be calculated. A misalignment of 1/1000˜ 1/100000 rad is possible inthe stage movement direction y and in a Y direction of a TDI or CCDsensor when this operation is performed. In addition, a misalignment of1/10000˜ 1/100000 rad is possible by adjusting at a high level ofaccuracy.

c) Next, Center Coordinates of a TDI Image Frame are Calculated (SeeFIG. 62, FIG. 63)

Because a TDI image is a two dimensional continuous image, a continuousimage is divided into frames by image processing. For example,1000×10000 Px, 2000×2000 Px, 4000×4000 Px etc are created as one frame.Adjustment and determination are performed so that the center of each ofthese frames matches the desired location. Here, an example of a methodfor determining desired coordinates is given.

A) For example, a pattern part of mark part that has a characteristic isused. These are arranged at the optical center location of the opticalmicroscope and their coordinate values are stored. In addition, theobtained start location and finish end location of the TDI image isdetermined so that the pattern part or mark part become the frame centerof a TDI image. Adjustment of the y direction location may be performedby image processing, that is, adjusting the parameters of the startlocation which divided a frame. Adjustment can easily be performed byadjusting the start location which divides a frame in 1 Px units. Forexample, adjustment is possible with an accuracy of 50 nm at 1 Px 50 nm,and 10˜500 nm/Px is usually used.B) Adjustment of a location in an x direction is performed by fineadjusting the coordinate location relationship of the optical centers sothat the desired pattern or mark move to the center location in an xdirection of the sensor. Alternatively, it is also possible to performfine adjustment using a last stage deflector. In this case, adjustmentwith an accuracy of 1/10 Px˜10 Px is possible. In addition, adjustmentwith an accuracy of 1/10˜1 Px is often used.C) Next, whether the desired pattern or mark has moved to the opticalcenter of a SEM (scanning type electron microscope) is confirmed. Ifthere is a misalignment, the coordinate relationship between the opticalcenters is corrected. That is, it is confirmed whether the desiredpattern or mark is at the center of the optical microscope, the framecenter of a TDI image and center of an SEM image and confirmed anddetermined that this is within an allowable value range. If it isconfirmed that the desired pattern or mark is within an allowable valuerange from the center of the optical microscope, TDI image frame of aprojection type optical system and SEM image, the distance between eachoptical center location is determined and stored in a memory etc. Anallowable value of 1 μm or less is possible. In addition, an allowablevalue of 0.1 μm or less is possible by a high level of accurateadjustment.D) Other than this, in the case where a detector used in a projectortype optical system is a CCD or an EB-CCD which forms an image bydirectly irradiating electrons to a sensor surface, because an image isobtained while the stage is in a stationary state, adjustment anddetermination is made so that the optical center arrives at the centerof the still image and a pattern or mark arrives at the optical centerof an optical microscope, projection type optical system EB-CCD image orSEM image within an allowable value range. This procedure and allowablevalue is the same as described above.

As described above, the present invention includes the features of A) astep of performing alignment using an optical microscope B) performingalignment in a direction of a detector sensor (y direction: calculationdirection of a sensor) using a projection type optical system C) a stepof calculating the optical center of an optical microscope, projectiontype optical system and SEM and storing correlated coordinates. Inaddition, in the case where a TDI image of a projection type opticalsystem is used, it is necessary to include a step of calculating a framecenter of a TDI image in step B).

In addition, in step C) it is possible to perform the followingprocedures when calculating accuracy with respect to a SEM image. The xdirection and y direction which form the image frame of a SEM image arecalculated and determined. The desired direction is obtained byobtaining a SEM image of a pattern or mark when step A) and B) describedabove are completed and misalignment of the x, y directions is extractedand corrected. The corrections means includes matching the directionwhile finely adjusting the misaligned x and y directions. In order toachieve this, 8 deflectors for forming a SEM image, that is, forscanning, are used. In this way, control of a deflection angle with anangle adjustment within 1/1000˜ 1/100000 rad is possible. It is possibleto perform this operation in step C).

In the example used in the devices of the present invention, a defectinspection is performed using a TDI image in a projection type opticalsystem after the operational steps pre-inspection described above arecompleted. In addition, a patch image and coordinate values of theinspection result are output and stored in a memory etc. Next, if areview is carried out using a SEM, review imaging is performed using aSEM of the parts in which defects are detected using a TDI image anddefect or false determination is performed.

At this time, it is possible to perform a defect determination or falsedetermination using a SEM image by an image processing device. Thefollowing methods can be used.

First, comparison of a pair of SEM images: Comparison with a referencepart image using a SEM

Second, comparison of a SEM image and TDI image (patch image). A patchimage is a defect image obtained during an inspection and is formed bycutting out the vicinity of a defect part detected from a TDI scan imageand stored in a memory. Usually, this is performed at around 50˜200 Px.It is preferable that the short side of an image is 1˜⅓ when this valueis the long side of an image.

In particular, in the second method, because image processing such aspattern matching is not performed sufficiently when the x, y directionof a SEM image are misaligned, it is necessary to perform adjustment anddetermination of the SEM x, y directions in advance. For example,pattern mismatching occurs due pattern location misalignment.

In addition, there is a method for correcting the x, y directions of aSEM image by image processing. A method of comparison is also possibleby calculating in advance the amount of correction of x. y of the SEMimage and making corrections when an image comparison with a TDI image.

Example 2

In the present example it is possible to clean adhered contaminationwhen performing a review using a SEM.

It is known that contamination such as carbon is adhered when performinga SEM observation. Because contamination is adhered when a SEM reviewobservation is performed, the contamination itself sometimes occurs as adefect. In particular, considerable contamination is generated in an endpart region of a beam scan.

Two methods are used in the present invention in order to solve thistype of problem.

First, a method of introducing a contamination reaction gas asimultaneously cleaning a sample surface while performing a SEMobservation.

Second, a method of cleaning using a projection type optical systemafter a SEM observation. A gas which has reactivity with contaminationis sometimes introduced and sometimes not introduced.

In the first method, a SEM review observation is performed whileintroducing an inert gas such as oxygen or oxygen+Ar, or a fluoridegroup gas such as SF6. In this way, although contamination occurs duringthe SEM observation, it is possible to remove the contamination byintroducing the gases described above which react with the contaminationand thereby causing a sublime gas state. At this time, it is importantto adjust the amount gas introduced to a level which does not affect thelevel of resolution of an SEM image. The effects are as follows. Theremaining gas particles within a vacuum chamber are excited by anelectron beam, polymerize with C or H to become contamination such ascarbon or DLC and adhere to the sample surface. The amount grows due inproportion to the amount of the irradiated beam and time. At this time,when the above described gases such as oxygen having reactivity withcontamination are introduced, the gas particles are excited byirradiation of an electron beam, become active gas particles and gasparticles having reactivity with contamination such as an oxygen radicalare formed. In addition, the active gas particles react with thecontamination, become gas particles such as CO, CO₂ etc and are removed.As a result, a SEM observation in a state where there is small amount ofadhered contamination is possible.

The second method described above is a cleaning method which can rapidlyremove contamination after a SEM review observation is performed. Anirradiation beam of a projection type optical system which irradiates asurface beam is used as the electron beam irradiation. At this time, theabove described inert gas is introduced, gas particles such as an oxygenradical are formed as an active gas by irradiating the surface beam ontothe gas particles and contamination is removed. The contaminationremoval effects are the same as described above. The merit of using thesurface beam is that it can be performed rapidly. Cleaning can beperformed by moving a stage at a speed of 30 mm/s with a 200×200 μmbeam, and irradiating an area region of about 100 mm for around 30minutes. A contamination removal process can be performed at a speed of2˜3 times that of a SEM type. At this time, in order to removecontamination efficiently, it is preferable to remove contamination of aboundary region where a SEM review is performed. Since a considerableamount of contamination is generated in this region, it is possible tosignificantly reduce contamination defects by removing the contaminationin this region and thereby, cleaning of this region is practical andoften sufficient.

As explained above, an entire structural view of a semiconductorinspection device in which an electron microscope, projection typeoptical system and SEM are arranged in one chamber is shown in FIG. 43already explained above. Since this structure has been explained indetail above, an explanation is omitted here. However, by adopting thisstructure, a spot can be specified with a high level of accuracy andalignment adjustment becomes easy. In addition, determination andclassification of an inspection of an ultrafine pattern of 100 nm orless can be performed efficiently and rapidly. Furthermore, the presentembodiment can be applied to the device in the first to eleventhembodiments described above. Providing the SEM and optical microscope ofthe present embodiment to a device including the same projection typeoptical system to the same device system and performing an inspectionand review is very effective.

Thirteenth Embodiment Particle Measures

Because the effect of particles increases together with miniaturizationtechnology the demand for measures to prevent particle adhering isbecoming stronger. When a device is realized for performing a defectinspection of foreign materials of 5˜30 nm or a pattern size as in thepresent technology, prevention of particles and prevention of particlesa size of the same level is required. While such prevention wassufficient in all conventional devices it is possible in the presentinvention. Particle prevention measures used in the inspection deviceand inspection method of the present invention are explained whilereferring to FIG. 64 and FIG. 65. Only the points of difference fromconventional measures are described.

Ceiling Cover Attachment (Effects)

Protection from Particles Falling from a Ceiling

A ceiling cover is attached so that a region of a sample which moveswith a stage is covered. In this way, an effect which prevents particleswhich fall from the top part of a column onto a main chamber including asample from being adhered to the sample is obtained. In addition, aconductor cover is arranged on the periphery of a sample surface such asa mask and becomes the same potential as the mask surface. In addition,the tip end part of the conductor cover has a thickness of around 10um˜300 um, a back surface contacts with a region having a conductionfilm of the sample surface and conducts. The thickness described here isprovided so that the effects of a change in a mask surface potentialnear the conductor cover are as small as possible. The width of theconductor cover extends in an exterior direction from the sample byaround 10˜130 mm. By reducing the distance between the conductor coverand ceiling cover the likelihood that particles which fall into thisspace collide or adhere the conductor cover and ceiling cover increaseand thereby it is possible to prevent particles from entering the samplesurface. In addition, by covering the sample surface to which a RTDvoltage is applied with the ceiling cover which has a GND potential, itis possible to prevent upper particles being attracted by an electricfield from the ceiling cover.

Dust Collector (Effects)

A dust collector is arranged which can suck and absorb particles whichare attracted from the periphery by arranging an electrode with the samevoltage on the periphery of a sample applied with a RTD voltage. Thisdust collector may be formed using one electrode or a plurality ofelectrodes. For example, in the case of two electrodes, it is possibleto increase dust collecting effects by providing different voltagesbetween the inner and outer electrodes. For example, by applying eithera higher or lower voltage than the potential of the sample surface,particles which have a positive charge are absorbed by the dustcollecting electrode which is applied with a low voltage and particleswhich have a negative charge are absorbed by the dust collectingelectrode which is applied with a high voltage. In this way, it ispossible to prevent particles from reaching the sample surface.

Ultrasound Motor Cover (Features)

Movable parts used with a vacuum chamber such as an ultrasound motor etcwhich are a source of dust generation within the vacuum chamber arecovered with a cover. Furthermore, particles are actively sucked andabsorbed by the cover by applying a voltage to the cover.

It is possible to capture particles adhered to a travel plate byarranging a travel plate cover on a travel plate movable part.

Stage Cable (Features)

Particles which are generated by the friction between cables are reducedby using single unit flat cables (Teflon (registered trademark)) forstage cables which move within the vacuum chamber.

A flat cable contact surface is arranged on a cable base (Teflon(registered trademark)) and friction between the cable and metal isremoved. In a usual cable, a resin usually covers the core which hasaround cross section. When there is a plurality of these, a plurality ofcables are bunched together and tied using an insulation lock. At thistime, particles are generated by friction between cables due to movementor transformation of the bunched cables together with movement of thestage. Furthermore, in the present invention, it is possible to apply astage cable to the device in the first to twelfth embodiments describedabove.

Fourteenth Embodiment (Axial Correction Inherent to an Electron Image)

Axial correction inherent to an electron image in an inspection deviceand inspection method of the present invention is explained.

It is possible to apply FIG. 26, FIG. 27 and their embodiments as anexample or as a reference. A DUV laser is irradiated to a samplesurface, photoelectrons are generated from the sample surface, amagnified image is formed at a detector by a secondary optical systemand a two dimensional photoelectron image is imaged. The RTD conditionsof the secondary optical system, for example, a surface potential ispositively charged due to photoelectron emission with respect to −4000Vby the setting of the photoelectron image formation conditions. Becausemisalignment occurs from RTD−4000V due to this surface potential, theamount of misalignment is corrected by changing the RTD potential.

(Simultaneous Irradiation of Light with Different Wavelengths)

An example of simultaneous irradiation of light having differentwavelengths to a sample W in an inspection device and inspection methodof the present invention is explained.

In the case of a sample such as a EUV mask having a pattern with anuneven structure, when the outermost surface layer which are the bumpparts are TaBO and the hollow parts are Ru, the contract between TaBOand Ru is sometimes TaBO>Ru (λ=266 nm), and sometimes TaBO<Ru (λ=244 nm)due to the wavelength. That is, when a sample surface having a patternstructure with TaBO and Ru is simultaneously irradiated with light oftwo types of wavelength, the pattern disappears and the parts (forexample, foreign materials) other than the material which forms thepattern are detected. This can improve particle inspection or detectionsensitivity of defects (foreign materials) of a pattern hollow part(Ru).

In the case of simultaneously irradiating light having differentwavelengths, because the quantum efficiency is each is different, it isnecessary to adjust the DUV light intensity or DUV laser intensity sothat the contrast between TaBO and Ru disappears. At this time, in thecase of laser irradiation, the laser irradiation intensity to a samplesurface is adjusted using a polarization filter by adjusting the anglebetween the polarization surface of the laser and polarization surfaceof the filter. Because the quantum efficiency is different due to thewavelength of the light, the amount of variation in the surfacepotential is different due to the material of the sample surface.

The energy of a photoelectron becomes 4000V in the case of a detectorsurface potential GND at RTD−4000V mentioned above. When the secondaryoptical system lens conditions are optimized by adjusting RTD, it ispossible increase a contrast difference and increase signal intensity byirradiating a light (laser) with a different wavelength to a wavelengthused in an inspection in order to match in advance the material to beseen as a white signal (the amount of electrons generated is relativelyhigh) and greatly displace other materials from the lens conditions.FIG. 33 (a) and FIG. 35˜FIG. 42 are examples of this. A laser isirradiated to a photoelectron surface chip, photoelectrons generatedfrom the surface are guided to a sample surface by a primary opticalsystem, photoelectron irradiation is performed on the sample surface asa primary beam, and secondary emission electrons from the sample surfaceare magnified and an image is formed at a detector by a secondaryoptical system. At this time, the wavelength of the laser irradiated tothe photoelectron surface chip may be larger than the work function of amaterial which forms the photoelectron surface and light with an energyas close as possible to the work function is preferred. In this way, itis possible to significantly reduce the dispersion of work energy heldby a photoelectron. That is, it is possible to reduce the energy band ofa primary electron beam compared to a conventional method. In this way,the energy dispersion of secondary emission electrons or mirrorelectrons which are generated by irradiating a primary beam (electrons)to a sample surface is also reduced and it is possible to obtain a sharpimage with few aberrations when forming an image. The photoelectronsurface chip structure includes coating a photoelectron material onto asingle surface of a base material having good laser transmittance, forexample, Ru, Au or Ag etc. A laser is irradiated from the rear side of acoating surface, photoelectrons are generated from the coating surfaceand photoelectrons are emitted in a direction opposite to the laserirradiation. In this way, it is possible to make the structure of a gunmore compact with the need for adding an angle between the irradiationaxis of a laser and the axis of a photoelectron.

Fifteenth Embodiment

Atmosphere Carrier which Carries a Double POD

An atmosphere carrier which carries a double POD in the inspectiondevice and inspection method of the present invention is explained whilereferring to FIG. 66.

(Operation/Conditions)

A double POD is a box having a double structure which encloses a samplesuch as mask. An inner POD includes a gap or a hole and the outer PODshould be open during load lock. At this time, the inner POD isstructured by a lower plate and an upper plate. A EUV mask patternsurface is arranged in proximity to the lower plate. At this time, theoperation flow is as follows. Outer POD opener→inner POD opener→rotationunit b→inversion unit→neutralization unit→palette loading unit→load lockchamber.

(Operation/Effects/Merits)

While the present invention is double POD compatible, it is possible touse a single and double POD together because the operation flow extractsa single mask using an inner POD opener. Furthermore, the presentembodiment can also be applied to the first to fourteenth embodiments.

Sixteenth Embodiment Compact SEM

A compact SEM used in the inspection device and inspection method of thepresent invention is explained while referring to FIG. 67.

A feature of the present invention is reviewing a detected defect withinthe same chamber as a defect inspection device (projection type electronbeam inspection device) at a higher magnification using a scanningelectron microscope (herein referred to as SEM).

(Effects)

Because it is possible to perform a review within the same chamber, asample is not moved between devices and thereby the sample is notcontaminated and time efficiency is improved.

A feature of the present invention is determining whether a detecteddefect is an actual defect or a false defect based on a review resultusing the SEM described above.

Automatic defect categorization (ADC) is performed using reviewed imagedata and the reliability of a defect detection result is increased.

A feature of the present invention is that the all the electron lensesin the SEM used for performing a review described above are formed byelectrostatic lenses.

A SEM structure using electrostatic lenses can also be used forobservation of an alignment mark since distortion of an image is smallin a low magnification observation.

(Effects)

In the case of an electromagnetic lens, a system for correcting thescanning shape of a beam is required in order to obtain an image withlow distortion at a low magnification. However, this is not requiredwhen using an electrostatic lens and thereby a simple system issufficient. In addition, in an electromagnetic lens a current is appliedto a coil in a lens structure, a magnetic field is generated and a lensfield is formed. As a result, 1˜5 hours is usually required until astable temperature and stable resistance state is reached after a deviceis started, that is, until an operation state of a lens is stable.However, an electrostatic lens reaches a stable state in a few minuteswhen certain voltage output setting is performed because a constantvoltage power supply is used. In this way, an electrostatic lens hasexcellent compatibility with condition setting or condition variation.Furthermore, this embodiment can also be applied to the first tofifteenth embodiments explained above.

Seventeenth Embodiment Adjustment Method of a Laser Beam

An adjustment method of a laser beam used in the inspection device andinspection method of the present invention is explained. The method canbe applied to FIG. 26˜FIG. 31 and related embodiments and are examplesof this method.

It is necessary to set a voltage of a secondary system lens etc to anoptimum value in order to increase of resolution of photoelectronsemitted from a sample surface, what is called optical axis adjustment. Ausual procedure of optical axis adjustment entails observing an imagewith an initial low magnification and performing a broad axis adjustmentin advance, then the magnification is gradually increased and an axisadjustment is performed at a high level of accuracy.

The amount of photoelectrons that contribute to image observationdecreases as the magnification increases. That is, if the photoelectrondensity is constant the magnification increases and when the Px sizedecreases the amount of photoelectrons per 1 Px decreases as the Px sizedecreases. Therefore, when a low magnification is changed to a highmagnification without changing power, the signal amount is insufficientand only a dark image can be obtained. In contrast, when an observationis made at a low magnification while maintaining an optimum laser powerat a high magnification, the amount of photoelectrons become saturatedand a required contrast can not be obtained. As a result, it isnecessary to adjust the power of a laser beam. However, it is oftenimpossible to adjust the power of a laser itself. In this case, it ispossible to adjust the power or a laser beam which reaches a samplesurface using an optical element such as a variable beam splitter, anattenuator, a polarization element or lens etc.

A variable beam splitter changes the proportion of transmitted light byadjusting the angle with respect to a laser beam using a plate shapedoptical element.

An attenuator is an integrated unit of a plurality of optical elementssuch as a variable beam splitter and can easily be operated.

A polarization element changes the transmittance due to the polarizationstate of a beam and changes the polarization state by changing thephase. A polarization element includes a polarization plate, wavelengthplate or depolarization plate and by combining these it is possible totransmit only a specified polarization state and control the power oflight.

For example, the focal distance of a lens is changed by changing thelocation of a plane-convex lens for collecting light, localized powerdensity of an observation range is changed by changing a power profileand the amount of photoelectrons can be controlled. Other than this, thethickness or number of transmittance substances such as a lens, orsilica glass etc may be adjusted and power may be adjusted by increasingthe number of mirror reflections.

Methods for adjusting the power of a laser other than the method usingan element such as described above are as follows. For example, powerdensity of an observation surface changes by changing the angle of amirror and changing the irradiation location of a beam. It is possibleto obtain a large amount of photoelectrons when a part with a high powerdensity is irradiated as the observation part and a small amount ofphotoelectrons are obtained when a part with a low power density isirradiated as the observation part.

A method which uses two or more types of light source with differentpower is also possible. For example, in the case of a low magnificationobservation, it is possible to use a mercury xenon lamp which hasultraviolet regions with little power, and it is possible to use a gaslaser has twice the harmonics of a YAG4 harmonic solid state laser or Arion laser in the case of observation at a high magnification. At thistime, it is possible to guide the mercury xenon lamp within a vacuumusing a fiber, and irradiate directly from the fiber exit or via anoptical element such as a mirror.

The laser beam irradiated from a laser transmits through a syntheticsilica view port via a first mirror, light collecting lens, secondmirror, and is guided to the inside of a vacuum chamber. After passingthrough the view port, the beam is reflected by a triangular mirrorarranged in the vicinity of a column axis center and is irradiated to asample surface at an angle misaligned about 0.1˜30° from the axis centerof an electron beam.

The triangular mirror has a hole having a diameter of 0.5˜5.0 mm so thatan electron beam can pass through the axis center and has a syntheticsilica or phosphor bronze surface which is coated with aluminum. Thepotential of the triangular mirror is made the same as a space potentialsuch as an earth potential so that the electron beam which passesthrough the triangular mirror hole is not bent by an electric field. Inthe case of manufacturing the mirror using a synthetic silica, it isalso necessary to coat the inside of the hole with aluminum in order tosecure conductivity.

A polarization element, beam splitter or attenuator may be arrangedafter a lens for example in order to adjust the power of a laser.

Although a method of arranging a mirror or lens on the atmosphere sidewas explained above, these lenses or mirrors may all be arranged withina vacuum chamber.

Eighteenth Embodiment

Inspection device for controlling an irradiation angle θ and irradiationdirection a of a beam to a sample surface

A method for controlling the irradiation angle θ and irradiationdirection a of a primary electron beam to a sample surface used in theinspection device and inspection method of the present invention isexplained.

(Difference from Conventional Technology)

A projection type electron beam device is disclosed in InternationalPublication WO2009/125603 in which the LE energy of an electron beam isgiven as a transfer region which includes both mirror electrons andsecondary emission electrons, an NA location is optimized, electronsemitted from a conductive material are extracted and a line and spacepattern or contact plug are observed at a high contrast.

In addition, a method of optimizing an NA location while observing anelectron distribution at an NA surface under lens conditions for imageforming an NA surface at a detector is disclosed in paragraph (0205) ofPatent Application 2010-091297. In this application, a method wasdiscovered for obtaining an image with an even higher contrast bycontrolling the irradiation angle and irradiation direction of a primarybeam to a sample surface.

FIG. 6 (B) of Patent Application 2010-091297 shows an exemplary diagramof an NA surface observation (FIG. 68).

The inventors found that in a cross over (CO) image in the NA imageforming optical conditions, a separate distribution (MC) of mirrorelectrons which rebound without hitting a sample to the distribution(CO) of secondary electrons which hit a sample within an ec distributionexists even if the LE of a primary beam is changed into a transferregion of secondary electrons and mirror electrons (FIG. 69).

An NA image formation exemplary view which corresponds to the exemplaryview in FIG. 3 of Patent Application 2010-091297 in which an image inwhich the image conditions LE which link NA stated above is shown inFIG. 70. At this time, a mirror electron region is defined when alanding energy is lower than LEA, a transfer region in which mirrorelectrons and secondary emission electrons are mixed is defined whenLEA≦LE≦LEB and a secondary emission electron region is defined whenLEB<LE. In addition, the following is an example when LEA=0.

Because about 2 eV exists in the case where an energy distribution for aprimary beam is a LaB6 chip, more than a few negative LE electrons existwhen a landing energy LE=0 eV. For example, CO and MC are sometimesexpressed simultaneously in FIG. 70.

This example is shown in FIG. 70. The furthest right diagram is a COcross section of secondary emission electrons and moving to the left, COdecreases because of an increase in the emission amount of mirrorelectrons and a decrease in secondary emission electrons, MC appears andits intensity gradually increases. When LE becomes negative only MCexists. The size of this electron distribution sometimes represents theemission angle distribution of mirror electrons or secondary emissionelectrons.

The trajectory of mirror electrons is changed in an opposite directionwhen a parabola is drawn due to the potential of a sample surface and aprimary beam forms an MC at an NA surface. That is, the location of MCcan be controlled by the irradiation angle of a beam.

On the other hand, because the secondary emission electrons which hitthe sample and are emitted are different to the primary beam (electrons)no effect is received from the irradiation angle.

A method for changing only the irradiation angle without changing anirradiation location can be realized by using a two stage deflector(BA1, 2) mounted on a primary column (FIG. 71).

The voltage and irradiation angle data of a two stage deflector in a Xdirection or Y direction is shown in FIG. 72.

The MC location is important with respect to CO in the case ofattempting to reduce the NA diameter in order to achieve highresolution.

When the NA is arranged at the CO center in an attempt to obtain a highresolution, MC mainly passes through the NA and an image is formed inthe case where a primary beam is irradiated at a perpendicular angle(FIG. 73). A good image can not be obtained since the MC does notinclude sample surface data.

Thus, a method was examined for obtaining a high resolution image bychanging the irradiation angle of a primary beam and offsetting an MCvertically and horizontally.

In the case of observing an L&S pattern, the bump (line) part of thehorizontal pattern becomes brighter due to the effect of an MC light inthe case of arranging an MC vertically, and the electron density in thebump (line) part of the vertical pattern becomes higher when an MC isarranged horizontally. In addition, the contrast of the vertical andhorizontal pattern can easily become non-uniform. In the case ofshifting the beam irradiation angle θ in the X direction and Y directionand making the irradiation direction to a 45° direction, the MC locationalso changes in a 45° direction within the NA surface. An image with agood contrast where the vertical and horizontal pattern are the same canbe obtained.

In the example in FIG. 74, the irradiation direction is defined as theX+ direction at 0° and an angle in an anticlockwise direction isdefined.

A voltage may be set to the voltage of the deflector which becomes adesired irradiation angle. An exemplary view of NA image formation isshown in FIG. 74 and a trajectory exemplary view of a mirror electron isshown by the trajectory A.

As MC approaches NA, the SN of a pattern improves. However, contrastdeteriorates and when MC moves further away from NA, SN deteriorates andthe contrast sometimes decreases. It could be experimentally confirmedthat an optimum location relationship exists when MC is at a distance2˜3 times the NA diameter from the center.

A method for adjusting an MC location can be easily realized whileobserving an NA image formation.

On the other hand, in the case of observing particles on a sample, itwas experimentally confirmed that a higher sensitivity can sometimes beobtained when observing in a vertical direction (X direction) than ahorizontal direction (Y direction).

In addition, in the case where the MC is arranged on the left or right(X direction), the left and right side of an image becomes brighter, andin the case of scan imaging in a Y direction either the left or rightside becomes brighter. In this case it is preferred to place the MCabout 2˜3 times the NA diameter form the CO center.

The merits of using an EB˜CDD or EB-TDI in these observations andinspections can be referred to in paragraphs (0403) and (0404) ofInternational Publication WO2009/125603. Furthermore, the presentembodiment can also be applied to the first to seventeenth embodimentsdescribed above.

Example 1 First Step

Sample: Cu/SiO₂ wire pattern (refer to FIG. 75)

Acceleration Voltage: −4005 [V]

Sample Surface Potential: −4002.6 [V]

LE=2.4 [eV]

Current Density: 1 [mA/cm²]

Secondary Optical System NA image formation TL2-2; 5550 [V]

An EB-CCD camera was used for a detector and an MC and CO were observeusing NA image formation conditions. Values of aligners BA1, 2 were setso that a sample surface was irradiated from an irradiation directionα=45[°] and irradiation angle θ=100 [mrad] (FIG. 76).

Second Step

Magnification setting of an electron optical system, square of 29 nm(pixel)

A 25 nm L&S pattern on a wafer was observed with an NA hole diameter of30˜100 μm. BA1, 2 and an NA location were adjusted and the L&S (line andspace) pattern became the same vertically and horizontally.

Third Step

MC location was 45° above the sample surface, an irradiation angle waschanged with a range of 20˜200 [mrad] and the contrast and S/N of theL&S pattern was measured. S/N was defined by dividing the contrast by astandard deviation a of an average grey level of a W surface.

The relative location of MC with respect to the NA diameter is shown inFIG. 77. From FIG. 77 a good image together with a contrast and S/Naround a relative location of 2.5 was obtained.

The relative location of MC and contrast and S/N correlation is shown inFIG. 78.

Fourth Step

Stage Speed: 1˜20 mm/s

Data Rate: 50˜100 MPPS

When an inspection was performed on a wafer while scanning using a TDIcamera, a defect detection of about 25 nm could be performed.

Example 2 First Step

Sample: Refer to FIG. 7 of Patent Application 2010-091287 regarding φ30nm φW contact plug/SiO2 structure.

Acceleration Voltage: −4005 [V]

Sample Surface Potential: −4002 [V]

LE=2.4 [eV]

Current Density: 1 [mA/cm²]

Optical System NA image formation TL2-2; 5550 [V]

A mirror electron (MC) and cross over (CO) at NA image formation wereconfirmed using an EB-CCD camera and a two stage deflector BA1, 2 wasarranged as follow (refer to FIG. 79). The values of BA1, 2 wereadjusted and a sample surface was irradiated from a 0[°] Y direction andan irradiation angle 100 [mrad] (refer to FIG. 80).

Second Step

Magnification setting of an electron optical system, square of 29 nm(pixel)

A W plug on a wafer was observed with an NA hole diameter of 30˜100 μm,and the contrast and SN correlation in [Third Step] described above weremeasured.

In this case also, an optimum image was obtained around a relativelocation of 2.5.

Third Step

Stage Speed: 1˜20 mm/s

Data Rate: 50˜100 MPPS

When an inspection was performed of a plug on a wafer while scan imagingusing a TDI camera, a defect inspection of a φ30 nm plug structure couldbe performed. An even higher contrast inspection can be informed byapplying the principle of a beam dose in FIG. 19 and contrast inversionin FIG. 22 in Patent Application 2010-091297.

Example 3 First Step

Sample: particles on Si

Adjustment of an irradiation angle with the same conditions as in [FirstStep] in Example 2 was performed.

Second Step

Magnification setting of an electron optical system, square of 100 nm(pixel)

Particles on a wafer were observed with an NA hole diameter of 30˜100μm, and the contrast and SN correlation in [Third Step] described abovewere measured. In this case also, an optimum image was obtained around arelative location of 2.5.

Third Step

Stage Speed: 1˜20 mm/s

Data Rate: 50˜100 MPPS

When an inspection was performed of particles on a wafer while imagescanning using a TDI camera with these conditions, an inspection at asize of φ10˜30 nm could be performed.

Nineteenth Embodiment

A high voltage power supply used in the inspection device and inspectionmethod of the present invention is shown in FIG. 81.

A superimposed type high voltage generation device and applicationexample are shown in FIG. 81 (a) and FIG. 81 (b). The high voltagegeneration part in FIG. 81 (a) receives a 20 kHz alternating currentsignal and superimposition of different potentials becomes possible. Theoutput side of an insulation transistor is converted to a direct currentby a rectifier circuit. The 20 kHz alternating current signal ispreferred to have a sine wave or rectangular wave which is not steep atstart up in consideration of preventing excess noise. The direct currentoutput is an energy source for obtaining a high voltage output, and isconverted to an alternating current signal by an inverter. Here too, asine wave or rectangular wave which is not steep at start up inconsideration of preventing excess noise is preferred. After convertingto an alternating current signal it is converted to several kV by aboosting transistor and converted to a direct current voltage which isboosted to a desired voltage by a boost rectifier circuit. The boostrectifier circuit is a usual Cockcroft Walton circuit. The boosteddirect current high voltage output is divided, compared with a voltagecommand value within a block of a voltage control function, thecomparison value is controlled to be minimally fed back and a constantoutput voltage is maintained. The voltage command value and a monitoroutput are converted to photoelectrons and are input or output byoptical fiber. The photoelectron conversion procedure includes a methodof converting the photoelectrons to a frequency proportional to avoltage value, sending as a two value signal of light, reverseconverting on the receiving side and returning to a voltage value whichis method conventionally performed. However, because this method broadlybelongs to ND, D/A conversion, other known methods can also be applied.

When a high voltage power supply is separated from a column, a highvoltage connector, high voltage cable and high voltage vacuumintroduction terminal is required for a connection. Because theserequire a resistance voltage in an atmosphere, a large element isessential in proportion to the voltage used considering the necessity ofmaintain a sufficient creeping distance. Therefore, this becomes a largeobstacle to the miniaturization of devices. A commercially availableconnector with a resistance of 30 kV, length of 200 mm and diameter of50 mm is required. On the other hand, in a vacuum pressure of 1×10⁻⁴ Paor less, the density of a gas molecule as a medium becomes sparse andthe resistance pressure of space significantly improves compared toatmosphere. In the present embodiment this point is utilized byarranging a high voltage generation block within the space adjacent toan optical system, and generation of a high voltage and supply arerealized within a high vacuum. Because an optical system requires a highvacuum and contamination is significantly detested, an optical systemand high voltage generation part are divided by a separation wall, ahigh voltage is supplied by passing through this separation wall, andboth are discharged by separate discharge systems. A light or acommunication cable of a control communication system for supplying alow voltage alternating current or direct current voltage from the highvoltage generation atmosphere side and controlling a voltage is requiredfor connecting to this high voltage generation unit. However, since thepotential is significantly low and around several V or less, it ispossible to achieve a small scale device with a small scale vacuumintroduction terminal. Furthermore, the present embodiment can beapplied to the first to eighteenth embodiments described above.

Twentieth Embodiment EO Correction

An example of EO correction in an inspection device and inspectionmethod of the present invention is explained.

(Outline)

A wafer is explained as an example of a sample. An exposure mask, EUVmask, nano-imprint mask and template can also be similarly used as wellas a wafer.

When imaging a beam from a wafer using a TDI, the location of the waferrequires accurate positioning. However, actually, the wafer exists on anX-Y stage and because positioning is mechanically determined, several100 μm to several tens of nm and a response speed of several seconds toseveral ms are practical accuracy values.

On the other hand, since design rules are miniaturized approachingseveral 10 mm, imaging relying only on the mechanical positioningdescribed above, the order of response time and positioning accuracybecome separated from the order of design rules and imaging accuracywhich is a significant obstacle to obtaining an accurate image.

The imaging sequence is performed by combining a step (x axis) and aconstant speed scan (y axis), and the (y axis) which performscomparatively dynamic control is has a control residual error which isgenerally large and considering prevention of image distortion, agreater level of control is being demanded.

An X-Y stage which is highly accurate and has excellent responsivenessis included for solving these issues. However, an EO correction functionwas devises for realizing control accuracy and speed of a beam to animaging part which are issues that can not be solved by a stage.

A basic method includes accurately confirming the location of a wafer ona stage with a delay of within several microseconds at a sub nm order bya laser interferometer system and a bar mirror arranged on an x-y axis,a mechanical aperture is driven by an automatic control loop, andpositioning is performed while considering time delay and residual errorfrom a target position. A control residual error of a positioning resultperformed using this control is calculated from the difference between atarget position generated within a control device and an actual positionobtained by a laser interferometer system. On the other hand, a beam isguided to an imaging device via several electrodes and a correctiondeflecting electrode. A correction deflecting electrode has asensitivity in which deflection is possible of around several tens of μmwhich is converted to distance on a wafer, and two dimensionaldeflection of a beam to an arbitrary location is possible by applying avoltage to the electrode. After a control residual error is calculatedby a calculation device, it is converted to a voltage using a D/Aconvertor, and applied to the correction deflecting electrode forcancelling the control residual error. It is possible to performcorrection close to the resolution of a laser interferometer using thisstructure.

A method in which the above procedure is used for the X axis (stepdirection) and synchronizing a transfer lock of a TDI which is animaging element with the movement speed of a stage and transferring forthe Y axis (scan direction) was also invented an alternative method.

The concept of EO correction is shown in FIG. 82. A command is output toa target position from 1, and provided to control feedback loops 2, 4, 5which include a mechanical actuator. This part equates to a stage.Feedback is performed via a position detector 5 as a result of aposition displacement which is driven and the position displacement of adrive system gradually converges to the target position from theposition command, however, a residual error is produced due to thebenefit limits of the control system. The actual position is detectedwith an order of sub nm by a position output system 6 (the laserinterferometer is used here), a difference with the position commanddevice 1 is detected by a residual error detector, then applied todeflector electrodes 9, 10 using a high voltage high speed amplifier 7,a voltage is applied to cancel the residual error. In the case wherethis function is not present, a function such as 14 is included forreducing a variation which is produced as in 13.

A detailed apparatus structure is shown in FIG. 83.

An X-Y stage can be provided with smooth servo characteristics bydriving an X axis using a servomotor 2 for an X axis drive and encoder 1and detecting a rough position and speed. A servomotor is used in thepresent example, however, a similar structure in an actuator such as alinear motor or ultrasound motor is possible. 20 is an output amplifierwhich drives a motor. Accurate position data of an X axis can realize aposition detection function which includes sub nm a resolution bycombining a mirror 7, interferometer 11, receiver 12, laser source 13,and interferometer board 14.

Each function related to the X axis described above are the samefunctions for the intersecting Y direction and are realized by 10, 22,4, 5 and 6.

An X-Y stage controller 19 performs overall control of these devices andthereby it is possible to two dimensionally operate a stage and realizecapabilities with an accuracy of several hundreds of μm to several tensof nm and a response speed of several seconds to several microseconds.On the other hand, an X reference value and Y reference value are outputfrom 19 to an EO corrector, position data output in 32 bit binary formfrom 14 passes a high speed buffer board 15 and an actual position isreceived by an EO corrector 23. After an internal calculation isperformed, and after voltage amplification by a high voltage high speedamplifier 25, 24, a voltage is applied to deflection electrodes formedfrom 28, 29, 30, 31, and deflection for correcting a residual error partis performed and an image data electron beam in which a positionmisalignment is minimized is guided to a TDI 26 (imaging element). 27 isa part for generating a timing signal for determining a transfer speedof 26 described below.

A function for generating a target position in a scan direction in thepresent device is described next.

EO correction is a function for correcting a position by calculating adifference between a target position and actual position and deflectingan electron beam in order to cancel this difference. However, thecorrection range is limited to a range of several tens of μm.

This electrode sensitivity is determined by a dynamic range, noiselevel, the number of bits of D/A converter of a high voltage high speedamplifier. However, a significant misalignment between the actualposition of a stage when scanning with respect to the target position isproduced compared to when stationary due to the gain of a control loopbeing limited. A divergence from the target position is around 400 μm inthe case of travelling at 20 mm/s, and even if the difference iscalculated and output as it is, the correction range is significantlyexceeded which saturates the system.

In order to prevent this phenomenon and avoid this problem, thefollowing procedure in performed in the present device.

This concept is shown in FIG. 84. 1 is a target position on a stagewhich moves at a constant speed during a scan and therefore increases ina direction line with time. On the other hand, a mechanical position 3of a stage as a result of actual control includes a mechanical vibrationof several microns and a stationary deviation 2 of around 400 μm. Whileit is possible to smooth position data when actually travelling using afilter as a means for removing this stationary deviation, a delay isalways produced due to a time constant of a filter, and when a timeconstant in which a ripple can be ignored is provided, a measurementstart area is significantly limited which leads to a significantincrease in the total amount of measurement time. Thus, in the presentinvention, at least the following calculation is performed in order todetect the stationary deviation. A difference between the actualposition and target position at the time of the previous scan iscalculated by accumulating at least 2 to the 16th power the number ofsamples. An average value 5 of the stationary deviation between thetarget position and the actual position is calculated by dividing thisaccumulation result by the number of samples. The combined targetposition 6 is calculated by subtracting the average value 5 of thestationary deviation from the target position 4 at the time of a presentscan. In this way, a structure is realized in which EO correction withina dynamic range such as the EO correction value 5 shown in FIG. 85 ispossible.

A block view is shown in FIG. 86. A target value 1 is subtracted fromthe actual position 2 and the previous accumulation is performed withinthe block 3 at the time of a scan. On the other hand, an average valueof a stationary deviation calculated the same as the previous time isoutput from 4. EO correction data 8 with no response delay or ripple isrealized by a combined target position 6 calculated by subtracting 4from 1 using a subtractor 5 and subtracting this value and the actualposition 7 from an interferometer.

The structure of a block difference average detection 3 in FIG. 86 isshown in FIG. 87. A calculation is performed in 3, 4, a word of a dataselector 5 is selected by the value of an accumulation counter 6, adivision quality calculation is performed and an average value of astationary deviation is output.

An example of a transfer clock of a TDI shown in FIG. 88 is described. ATDI is an imaging element which aims to improve sensitivity and reducerandom noise by connecting several photoelectron elements in stacks in ascan direction and transferring the charge of each imaging element to afollowing element. However, as is shown in FIG. 88, it is important thatthe imaging object on a stage and an a pixel on the TDI correspond oneto one and when this relationship is broken, image distortions occur. InFIG. 88, the relationship between 1-1 and 1-2 and the relationshipbetween 2-1 and 2-2 show the case where each are in a synchronizedrelationship respectively, and the relationship between 3-1 and 3-2 andthe relationship between 4-1 and 4-2 show the case where synchronizationof is misaligned respectively. TDI transfer is synchronized with anexternal pulse and transferred to the next stage, thereby when a stageis moved one pixel at a time, this can be realized when a transfer pulseis generated.

However, since the position data output of a currently mainstream laserinterferometer is in a form which synchronizes a 32 bit binary outputwith 10 MHz internal block and outputs, it is not easy to realize as itis. In addition, the accuracy of a transfer pulse is also importantgiven a resolution of several nm, and high speed highly accurate digitalprocessing is required. The method invented in the present example isshown in H-1.

FIG. 89 is explained. Information data of a laser interferometer and a10M synchronized signal are introduced to this circuit. The 10M clock 2generates a 100 MHz clock synchronized by PLL 4, and is supplied to eachcircuit. A calculation process is performed each time thissynchronization signal generates a 10 state. The actual position data isheld in 22 and the previous value us held in 24. The difference betweenthese two is calculated by 26, and the position difference for each 10state is output from 27. This difference value is loaded as a parallelvalue to a parallel serial convertor 14, synchronized with a 100 MHzclock and the difference is output as the number of serial pulses from16. 15 also has the same function, however, a structure where operationis possible without rest at each 10 state is possible by combining 11,12, 13, 6, 7 and 8. As a result, a serial pulse corresponding to aposition difference is output for each 10M to a counter 17 by asummation circuit 16. If a comparator 18 is offset in advance when theresolution of the laser interferometer is 0.6 nm and 1 pixel is 48 nm,the counter outputs a pulse 19 at a timing equivalent to 1 pixel. Anoperation synchronized with the variation in speed of a stage ispossible by changing this signal into an external pulse from a TDI andit is possible to prevent distortions or blurring.

A timing chart is shown in FIG. 90.

1 is interferometer coordinate (position) data and the numerals areshown as examples of a position. 2 is a 100 MHz synchronized signalcreated by PLL. Bank A is an operation timing of a parallel serialconverter group (14 in FIG. 89) and bank B is 15 shown in FIG. 89. Adifference calculation timing 8 is performed after a latch timing 7 forstoring position data, a value is loaded to the parallel serialconverter (14 in FIG. 89), and 4 is output using a 1 cycle pulse of thenext 10M clock 3. Bank B performs the same operation at a timing delayedby 1 cycle of the 10M clock 3, and pulse generation 6 is easilyrealized. Furthermore, the present embodiment can also be applied to thefirst to nineteenth embodiments described above.

Twenty First Embodiment

An example of a palette used in the inspection device and inspectionmethod of the present invention is explained while referring to FIG. 91.

(Formation, Structure)

[Base] manufactured from aluminum or titanium. Electrostatic chuckadsorption surface (requires a flat surface). Arrange a RTD contactpart. Arrange a pin for supporting a mask.

[Handling part] manufactured from aluminum or titanium. Handling devicein atmosphere and vacuum robot.

[Frame] manufactured from phosphorous or titanium. Covers the mask uppersurface 1.2 mm from an end.

[Application Pin] manufactured from phosphor bronze. RTD is applied tothe mask upper surface. Wire is drawn around the application pin from anapplication part of the base.

(Operation, Conditions)

Frame is moved vertically by using a separate drive mechanism whicharranging a mask within the palette.

(Effects, Merits)

The following effects can be obtained when a palette is used and not amask single unit.

When the palette of the present invention is used, a part of the rearsurface of a mask is supported. There is no contact with a patternformation part. Consequently, damage by an electrostatic chuck and theattachment of foreign materials to the mask can be prevented. That is,when the mask is directly arranged on the electrostatic chuck mechanism,the rear surface of the mask is sometimes scratched and bad effects dueto the attachment of foreign materials are produced. In particular,because high accuracy and setting conditions are demanded in the case ofan EUV mask or nano-print mask, prevention of the attachment of smallsized particles is necessary. For example, prevention of 30˜50 nmforeign materials is necessary on the rear surface of an EUV mask andprevention of 3˜20 nm foreign materials is necessary on a nano-printmask is necessary due to poor exposure.

The palette of the present invention includes a contact mechanism on apart of the interior periphery part of the frame for applying a voltageto the mask rear surface. As a result, since the frame is set to thesame potential as the mask application voltage, it is possible toachieve potential uniformity at the end part of the mask and apply avoltage to the rear surface (surface conductive mask) of the mask whichis stabilized by the frame arrangement. That is, it is possible to applya RTD voltage from the upper part of a stable mask.

A movement part within a vacuum could be removed by providing the framewith the effects of a correction ring. That is, since the mask moves ina vacuum due to the arrangement of a palette, there is no movementbetween the mask and these arrangement parts. Consequently, it iseffective in prevent the attachment of foreign materials since there isno friction. Furthermore, the present embodiment can also be applied tothe first to twentieth embodiments described above.

Twenty Second Embodiment Method of Applying a High Voltage to a VacuumMovable Part

A method of applying a high voltage to a vacuum movable part used in theinspection device and inspection method of the present invention isexplained while referring to FIG. 92.

Application

In a device where a sample is transferred to the inside of a vacuumchamber and demonstrates functions by applying a voltage to the sample,a high voltage power source such as the voltage applied to a sample in aprojection type optical electron inspection device, which is −4000 [V]+or −5 [V] and the voltage applied to a sample in the example in FIG. 42previously described, which is −20˜−50 [kV] are sometimes applied to amovable part. At this time, a high voltage power source is arranged onthe stage (for example, on an x, y stage) of a vacuum chamber and theuse of a high voltage line as a movable cable us avoided, that is, ahigh voltage is applied to a sample with a cable wire that does notmove. Furthermore, by limiting an electrical lead wire from theatmosphere side to a low voltage signal, it is possible to easily use ahigh voltage. The wire cable from the high voltage power supply becomesthicker and therefore it is possible to not only reduce the generationof particles by using a cable which does not move, but also remove theneed for a large feed through, improve the efficiency of design andmanufacture and reduce costs.

In addition, the high voltage power source which is applied to a sampleas described above is arranged on a movable part such as a stage and ahigh voltage wire does not exist on the movable part. In addition, anexternal low voltage power source is superimposed on the high voltageapplied to the sample, and it is possible to control a high voltagevalue. Furthermore, the present embodiment can also be applied to thefirst to twenty first embodiments described above.

Twenty Third Embodiment Method of Improving the Detection Efficiency ofa Defect in a Defect Inspection Device

A method of improving the detection efficiency of a defect in a defectinspection device used in the inspection device and inspection method ofthe present invention is explained while referring to FIG. 93 and FIG.94. In each of the diagrams, (a) shows an electron microscope, (b) is anexemplary diagram of the electron microscope. The electron microscopeimages the shape of a beam at an NA location in a projection typemethod. Conditions for forming an image in the shape of a beam of an NAlocation on a detector surface using a lens between the NA and detectorare formed and imaging is performed. In this way, data such as the shapeof the beam, profile, and center location etc is obtained, and it ispossible to adjust the desired beam location (mirror electron) to adesired location, and set the NA to an optimum location.

This method is a method for improving the defect detection sensitivityof a defect inspection device using a projection type method by changingthe irradiation angle of a primary electron beam which is irradiated ata perpendicular angle in the conditions for obtaining an image usingboth secondary emission electrons and mirror electrons.

In the device described above, this method is a method for improvingdefect detection sensitivity by projecting detects on a detector largerthan the actual defect size by changing the irradiation angle of aprimary electron beam which is irradiated at a perpendicular angle.

The location of a mirror center which is the center of a beam of mirrorelectrons is adjusted within a range of 100˜800 μm in the scan directionside with respect to the center of a cross over when an NA image isobtained.

By adjusting the mirror center location in a direction further away fromthe cross over center in a scan direction than adjusting the mirrorcenter location to the center of a cross over, a very bright regionwhich appears from a defect is expanded.

In the case where secondary emission electrons are generated in a partwhere there are no defects and mirror electrons are formed in a partwith defects, the region of mirror electrons is expanded by performingthe adjustment described above, thereby, the detection sensitivity ofultrafine defects is improved by utilizing the expansion of a verybright region.

Twenty Fourth Embodiment Uniform Stable Supply of a Sample SurfacePotential

An example of uniform stable supply of a sample surface potential in theinspection device and inspection method of the present invention isexplained while referring to FIG. 95, FIG. 96 (A) and FIG. 96 (B).

It is necessary to apply a voltage to a sample surface in a defectinspection device using a projection type method.

The appearance of a surface state and defect is adjusted by changing thevoltage applied to a sample surface.

That is, when the voltage distribution of a sample surface is notuniform, conditions change due to the differences in the voltagedistribution and problems of reproducibility arise.

Therefore, an application method is proposed so that a voltagedistribution of a sample surface becomes uniform.

A high voltage is applied to a sample surface by connecting an outputfrom a high voltage power source to a part which contacts with the masksurface.

The area which contacts with sample is broadened.

The part attached with a sample application electrode is called a frameand it is possible to transfer the sample to the interior by moving theframe vertically.

When the frame is in a lowered state, the sample application electrodecontacts with the sample surface and it is possible to supply a uniformvoltage to the sample (refer to FIG. 96A).

Furthermore, using a separate frame structure is effective for applyinga uniform and stable voltage. An example of this is shown in FIG. 96(B). Referring to the lower surface diagram (FIG. 96 (b)) and uppersurface diagram (FIG. 96 (C)) of the frame shown in FIG. 96 B, the uppersurface forms a smooth finished surface of a frame structure with nobumps, for example, a 195×195 mm titanium or phosphor bronze plate, anda 146×146 mm hole is opened at the interior. In addition, there arebumps at 3 places as shown on the rear surface. These bumps have aheight of 10˜200 μm. The tips of these bumps may be sharp. A voltagehaving a defined value is applied to a rear surface layer of a maskusing the frame (cover). In the present invention, the mask is arrangedon a palette. The palette includes a mask support pin and above this anexposure mask such as a EUV mask is arranged. A material in which fewparticles are produced is used for the mask support pin. A metalmaterial coated with a resin such as polyimide, Teflon (registeredtrademark) or fluororesin or a part made of resin can be used. The masksetting location of the support pin contacts further to the exteriorthan the 142×142 mm mask interior. When a mask is arranged internally onan exposure device, the mask leans diagonally when foreign materials orparticles become attached and therefore the support pin prevents theattachment of foreign materials or particles on this region. Inaddition, it is also possible to contact and fix the support pin tocorner part of a side surface and bottom surface of a mask. In thiscase, a surface structure is adopted whereby the contact part becomesdiagonal to a defined angle. In addition, in order to prevent locationvariation of a mask when moving a stage, it is possible to arrange amask fixing guide pin for location fixing.

A EUV mask is arranged as described above. A usual EUV mask has aninsulation film on the uppermost surface and below this a conductingfilm. Therefore, it is necessary to break the insulation film of theuppermost surface and ignite the conducting film in order to apply auniform and stable voltage to the mask surface. At this time, a frame(cover) which includes bumps as shown in FIG. 96B is effective. Adefined voltage which is to be applied to the mask surface is applied tothe frame. In addition, as is shown in FIG. 96B, the frame is arrangedfrom above the mask. At this time, the bump parts break the insulationfilm and reach the lower conducting film making it is possible to applya stable voltage. When these bump parts are present they become partsfor applying a voltage to the mask and therefore it is possible tospecify a voltage application part, that is, it is possible to apply avoltage by controlling these parts. In addition, since these parts arethree contacts points, it is possible to arrange the mask upper surfaceand frame with a good level of parallelism. In an arrangement with twocontact points, the frame begins to lean and in an arrangement with fouror more contact points it becomes difficult to specify which bumpactually breaks the insulation film and applies the voltage to theconducting film. In addition, similarly, in the case where there are nobumps, it is difficult to specify which part is in contact with a mask.This is because it is likely that a different contact state is producedeach time a mask is replaced. At this time, since a usual thickness ofan insulation film of a EUV mask is 10˜20 nm, it is preferred to arrangea frame weight suitable for breaking the insulation film.

In addition, when the frame makes contact it is necessary to reduce adifference in level between the mask surface and frame. This is becausea non-uniform electric field distribution is produced due to thisdifference. When an inspection is performed on a mask end part, that is,on a part near the frame, the trajectory of electrons become misaligneddue to the non-uniform electric field distribution, and a misalignmentbetween coordinates and center location of an electron image issometimes produced. As a result, it is necessary to reduce thedifference in level between the frame and mask surface to a minimum. Thepresent embodiment adopts a structure reduced to 10˜200 μm. A leveldifference of 10˜100 μm is more preferable. In addition, a method forreducing the plate thickness near the mask contact surface of the frameis also possible. Furthermore, the present embodiment can also beapplied to the first to twenty third embodiments described above.

Twenty Fifth Embodiment Photoelectron Image Formation Using Light/LaserIrradiation

Photoelectron image formation using light/laser irradiation in theinspection device and inspection method of the present invention isexplained. The sample having an uneven surface such as in FIG. 53 (a),(b) and FIG. 57 is an example of the object sample. An exposure mask,EUV mask, nano-imprint mask and template and semiconductor wafer can beused.

(Irradiation of a Sample Using Feed Through and a Triangular Mirror)

The embodiments in FIG. 26˜FIG. 32 are example which can be applied.

An explanation of a triangular mirror in a vacuum and other lenses in anatmosphere was given above. There are also embodiments which can bearranged in a vacuum other than a light source. Light scattering orvibration occurs when there is an atmosphere, rubbish or dust in thepath of a irradiated light with a large energy such as UV, DUV, EUV andX rays, and instability of a an irradiation system is increased whichleads to a deterioration of optical elements such as a lens or mirror.In other words, oxide film formation of an element surface and filmquality of parts impacted with light deteriorates and surfacedeterioration occurs due to the attachment of dust or rubbish. A deviceand method can significantly reducing this problem by arrangingengineering components in a vacuum. In this case, after arranging aseparate chamber which contacts with a main column and adjusting anoptical axis in an atmosphere, a vacuum exhaust of the optical system isperformed. It is possible to easily perform an atmosphere release/vacuumexhaust in the case of a separate chamber of only the optical system.When there is a column and vacuum conduction in an electron engineeringsystem, since both the main column and main chamber must be released ofan atmosphere together, vacuum exhaust and atmosphere release must alsobe performed on unrelated parts. This leads to significant costs andtime loss.

(Optical Axis Adjustment Via an Atmosphere Side Mirror/Lens, IrradiationSize Adjustment Via a Lens Location)

It is possible to adjust the location and size of an optical axis andoptical irradiation within a main column in a mirror lens system on theexterior side of a main column. Adjustment of an optical axis, that is,shirt and tilt, is performed using two or more mirrors beforeintroducing a light to the main column. In this way, adjustment isperformed so that the center of an irradiation light arrives at theirradiation location of a sample. At this time, it is also possible toadjust the angle in a perpendicular direction of the sample surface,that is, an irradiation angle.

In addition, adjustment of the size of an irradiation light is possibleby changing the lens location in an optical axis direction. For example,it is possible to adjust the size of an irradiation light by reducing orincreasing the distance from the lens location to the location of thesample surface shorter or longer than f in the case where the focaldistance of f300 mm. φ5˜1000 μm, about 1/200˜×1 magnification of a laseroutput light diameter.

(Adjustment of Light Output Compatible with a Secondary SystemMagnification Using an Attenuator, Secondary System Optical Adjustment)

In optical axis adjustment of a main column, that is, axis adjustment ofa photoelectron, when photoelectrons are used in light irradiation it isnecessary to control the amount irradiation light according to themagnification of an optical axis of a main column. If the same lightirradiation density (amount) is used, in the case of low magnification,the amount of electrons which reach the detector becomes large and inthe case of a high magnification, too many electrons are detected andthe detector becomes saturated. As a result, an attenuator or beamsplitter is arranged on the optical path of the exterior side of themain column in order to change the density of light which is irradiatedand it is possible to adjust the power of the irradiated light. It ispreferred not to change the output of the light source itself in orderto maintain stable operation. In addition, this is particularlyeffective when the irradiation size is left unchanged. It is alsopossible to change the light irradiation size by changing the density oflight irradiated. In the case of a low magnification, adjustment isperformed by reducing the density of the irradiation light and in thecase of a high magnification, the size which is irradiated is reducedlight density is increased and image adjustment is performed. Inaddition, it is also possible to adjust an image by combining adjustmentof the output light which is introduced and control of the size of thelight which is irradiated.

(λ<264 nm: Ru white signal, TaBO black signal, λ>264 nm: Ru blacksignal, TaBO White Signal)

A work function WF of a material is a value inherent to a material whichoutputs light when a large energy is irradiated than the energy of thework function value. An optical wavelength corresponding to the WF isgiven as λWF. There is a method for imaging in a state where there arefew photoelectrons by selecting a wavelength with a higher energy thanthe WF of a sample and selecting a wavelength with a lower energy thanan image which generates many photoelectrons and WF.

In addition, in a sample where a plurality of materials are mixed, theimaging method which has the following characteristics is possible inthe present invention. At this time, for example in the case where theretwo materials 1 and 2, each are given as WF1, λWF1, WF2, λWF2. Thewavelength of the light which is irradiated is given as λ.

A: In the Case where λ<λWF1<WF2

Observation is made with a contrast where a higher emission efficiencyof photoelectrons is a white signal and a lower efficiency is a blackmaterial between the materials 1, 2.

B: In the Case where λWF1<λ<WF2

Because the material 1 has the relationship light energy <WF1, theamount of photoelectrons from the material 1 is significantly reduced.Consequently, an observation is made where the material 1 is black andthe material 2 is white (material with a relatively larger amount ofphotoelectrons is called a white signal and the material with a smalleramount of photoelectrons is called a black signal).

C: In the Case where λWF1<λWF2<λ

Since both materials have the relationship light energy<WF1, WF2, theamount of photoelectrons of both material 1 and material 2 issignificantly reduced. Therefore, it is difficult to determine which iswhite and which is black.

In this way, it is possible to obtain a contrast is the cause of adifference in the amount of photoelectrons by selecting a lightwavelength, and irradiating a light or laser with a higher energy thanthe work function of a plurality of materials, and since the energy bandof a photoelectron is small compared to a secondary electron etc (forexample, ⅕˜ 1/20)), aberrations are small and a high resolution can beachieved.

In the case of A described above, when a material is selected with ahigh photoelectron emission efficiency for the material 1, and amaterial is selected with a low photoelectron emission efficiency forthe material 2, imaging with a high contrast is possible (contrast0.5˜1.0).

In the case of B described above, since the material 1 provides a lowerenergy wavelength than λWF1, the amount of photoelectrons in material 1is low, however, since the material 2 is irradiated with light (or alaser) having a higher energy wavelength then WF2, many photoelectronsare generated in material 2. Consequently, it is possible to image apattern with a relatively high contrast using material 2 as a whitesignal and material 1 as a black signal.

In the case of C described above, since the material 1 is alsoirradiated with a lower energy wavelength than the work function of thematerial 2, the material 1 is in a state with few photoelectrons. Atthis time, when there are defects such as foreign materials with a lowwork function, these defects generated photoelectrons and the defectscan be detected.

In this way, it is very effective for imaging to select the wavelengthof an irradiated light or laser (energy of a laser is selected) to asample formed from a plurality of materials such as a mask, EUV mask,semiconductor wafer, nano-imprint mask etc with respect to the workfunction of each material, and the wavelength which generated manyphotoelectrons is selected, and it is possible to image a pattern with ahigh resolution and foreign materials with a level of sensitivity. Atthis time, in the case of two of more materials, it is effective to usea method for forming a relatively large/small amount of photoelectrons.In addition, in the case of three of more materials, it is effective toform a state where only one material generates a large amount ofphotoelectrons. At this time, a sample such as a mask, EUV mask,semiconductor wafer or nano-imprint mask etc is often formed with anuneven structure which is particularly effective. It is possible to formconditions where only the top layer generates many photoelectrons andperform imaging or defect inspection. Because a pattern shape can beclearly imaged, this is effective for pattern defect imaging orinspection. In addition, it is effective for an observation orinspection of a hollow part defect to select conditions in which thereare many photoelectrons generated from a material of a bottom surface ofa hollow part. At this time, it is particularly effective when a patternsize, for example, line/space, half pitch (hp) size, or hole shape sizeis smaller than the light wavelength. For example, in an opticalinspection device defects of a pattern etc are observed or inspectedusing scattered light of a light which is irradiated, however, when thesize is smaller than the wavelength, the resolution drops significantlydue to a wavelength limit, the resolution of a pattern decreases due toscattered light and observation or inspection of a pattern becomesdifficult. In order to overcome this, the method which usesphotoelectrons in the present invention can perform an observation orinspection of a pattern at a high resolution even in the case where apattern size is smaller than a light wavelength. As stated above, 1) Itis possible to increase contrast by selecting a wavelength with respectto the work function of a material, and 2) it is possible to generatephotoelectrons by forming a near field in the case of a pattern smallerthan a wavelength, thereby, it is possible to generate photoelectronswhich reflects the shape of a pattern, and thus achieve high contrastand high resolution. For example, if a state is formed where only theamount of photoelectrons in the top layer is high, it is possible toform a pattern where the top, that is, line part (bump parts) is white.In addition, if a state a condition is formed where only the bottomsurface of a hollow part has a large amount of photoelectrons, it ispossible to perform an observation or inspection with a high resolutionwhere the hollow part (space part) is a white signal. When forming theseconditions, the methods A, B, C stated above are selected and performed.In addition, in the case of three of more materials, for example, in thecase of a top layer, hollow part and wall part, a condition is formedwhere only the top layer generates a large amount of photoelectrons. Itis also possible to form a state where only the hollow part (space part)generates a large amount of photoelectrons and form a state where onlythe wall part generates a large amount of photoelectrons.

In addition, it is more effective to combine these states for use inimaging and inspection. For example, when an observation or inspectionis performed in a state where only a top layer (bump part) generates alarge amount of photoelectrons and a state where only a hollow part(space) generates a large amount of photoelectrons, each defect isextracted from the result of both, and it is possible to detect apattern shape defect, ultrafine foreign material defect in a hollow partor film defect etc and therefore, an observation or inspection can bethoroughly performed. In addition, it is also possible to perform anobservation or inspection by simultaneously forming a state where alarge amount of photoelectrons are generated in a top layer and a statewhere a large amount of photoelectrons are generated in a hollow part.At this time, the pattern resolution becomes poor resulting in a greystate (an intermediate color between white, black) due to a combinedimage. In addition, because parts which include defects aresignificantly misaligned from this color, that is, become white orblack, it is preferred to detect only foreign materials or patterndefects. In particular, detection is easily performed in the case offoreign materials on the top layer of a pattern, however, this isparticularly effective for detecting ultrafine foreign materials in thehollow parts of an uneven pattern. Only these ultrafine foreignmaterials become white or black and therefore it is possible to performdetection with a high contrast. As a result the amount of photoelectronsbeing different due to a difference in work functions of differentmaterials or in the case where the potential distribution within ahollow part changes due to ultrafine foreign materials in the case ofsame materials, the trajectory of the photoelectrons changes and theamount of photoelectrons reaching the hollow part is large anobservation is performed with a relatively white signal and with a blacksignal when they are few. In addition, it is possible to perform anobservation with a black signal when the amount of photoelectrons ofultrafine foreign materials is few and with a white signal when theamount is large. In addition, an inspection is performed using thesemethods.

For example, in the case of an EUV mask, a structure where a top layeris formed from TaBO and a hollow part is formed from Ru is often used.In addition, the work function of Ru is 4.7 eV and relative wavelengthis 264 nm.

At this time, by selecting or combining a wavelength λ of a light orlaser which is irradiated as in the conditions A, B, C above, it ispossible to perform an observation or inspection where a top layer is awhite signal and a hollow part is a black signal.

For example, a state where there are many Ru light signals of a hollowpart where λ<264 nm, that is, observation or inspection is possible witha white signal. In addition, in the case where λ>264 nm, an observationand inspection is possible where TaBO of a top layer is a white signal.

At this time, it is possible to form an image having symmetry in avertical, horizontal, diagonal line/space pattern by irradiating a lightand/or laser from many directions. It is possible to perform irradiationfrom 4 or 8 directions. In addition, it is effective to performirradiation of a light or laser by selecting or combing T/M directions.

Because the distribution of a near field (energy field transmitted to apattern size region smaller than a wavelength) formed on the patternsurface is significantly different due to a pattern direction, light orlaser irradiation direction to the pattern and polarization direction,it is possible to select and use conditions for obtaining a highcontrast.

That is, it is possible to perform an observation or inspection byselecting conditions for obtaining a strong near field in a top layer orstrong near field in a hollow part.

At this time, the effects of interference or diffraction are sometimesreceived when using a single wavelength laser. An unnecessarywhite/black pattern is sometimes formed due to these effects. Thewavelength width may be broadened in order to avoid these effects, forexample, + or −1˜2 nm. In addition, it is effective to simultaneouslyirradiate lasers having different wavelengths.

In addition, it is effective to make a polarization directionmultidirectional instead of one direction, so that the effects ofinterference or diffraction are significantly reduced. In addition, italso effective to perform imaging while continuously changing thepolarization direction. An image which can be obtained within anexposure time by changing a polarization direction within the time forimaging one frame becomes an integrated image and an image with feweffects from diffraction or interference can be obtained. Furthermore,the present embodiment can also be applied to the first to twenty fourthembodiments.

Inspection Method/Device Using Scattered Light from EUV LightIrradiation

It is possible to perform an inspection of a EUV mask using the samemethod and device as in FIG. 1˜FIG. 25 which describe a device system.In this example, EUV light is irradiated to a sample. A pattern image isformed by the light (or EUV light) reflected from an uneven pattern ofan EUV mask using a mirror system and detection is performed by adetector. Following this, it is possible to detect a defect using signalprocessing. An inspection can be performed using cell/cell, die/die ordie/database etc. A wavelength of 13.5 nm is used in EUV exposure.However, it is also possible to use a similar method and device systemfor a wavelength in a soft X ray region.

Loss in transfer and irradiation within an atmosphere and in inspectionimage formation is large because the wavelength of EUV is short andcontamination and noise increases due to ion formation of atmosphereparticles which is inefficient. Consequently, light transfer,irradiation and image formation is required in a vacuum device system.At this time, it is possible to apply the vacuum device system of thepresent invention.

EUV irradiation is the same as the examples described in relation toFIGS. 8, 9 and FIG. 26˜FIG. 32. The difference between the examplesdescribed above is that a pattern is formed using light or EUV lightwhich is reflected or scatted from a EUV mask in a primary opticalsystem. A secondary system is a magnification optical system in whichmirror electrons and secondary emission electrons are not used but EUVreflection mirrors are used instead of an electron electrostatic lens ormagnetic lens. An image is formed, magnified and projected in a detectorusing this optical system. The optical magnification is 500˜3000 and 3˜4Px/line is achieved for a L/S pattern for example. The advantage of EUVlight irradiation is that the reflectance ratio of a hollow part of anuneven pattern is high. In addition, the reflectance intensity of ahollow part is high and low for a bump part since a side wall part orbump part become an adsorption layer with respect to EUV light, andtherefore a high contrast and S/N can be achieved. At this time, it ispossible to use EB-TDI or EB-CCD as a detector. This is because EUV hassensitivity even if electrons are not irradiated since the energy of EUVlight is high. In addition, it is possible to adjust the optical systemor image formation conditions using an EB-CCD.

In addition, it is possible to form a continuous inspection image usingan EB-TDI and perform an inspection at high speeds. At this time, alinked operation between a stage and the EB-TDI is performed, theobtained amount of light is increased by a calculation of an image andit is possible to obtain an image with a high S/N and perform aninspection at high speeds. An EB-TDI, EB-CCD have a sensor part arrangedin a vacuum. Not only these detectors but detectors which have sensorsthat can be arranged in a vacuum or elements which can form a twodimensional image can also be applied. For example, a scintillator+TDIetc. In addition, in a primary optical system which an optical system ofEUV reflected light, it is possible to coat a thin film of TaBN orcarbon on a surface of a part other than a column surface or mirror inorder to reduce reflectance due to EUV or noise due to the generation ofphotoelectrons.

In addition, when a EUV mask top layer includes an oxide film, a controlelectrode is arranged near the sample as in FIG. 192 in order to controlcharge up of the EUV mask surface due to EUV light irradiation, thereby,the sample surface potential can be controlled.

For example, when a EUV mask itself is connected to GND, photoelectronsare emitted from a top layer oxide film when irradiated with EUV lightand the oxide film is positively charged. In order to control this, anegative electric field is generated near a mask surface, that is, themask surface is set to a relatively positive potential. In this way, itis possible to control to charge up when the generated photoelectronsreturn to the oxide film. Other than this, a method for applying apotential of about 3˜10V to the EUV mask surface and applying a negativepotential in advance is effective. Furthermore, the present example cansimilarly be applied to the first to twenty fifth embodiments other thanthe secondary optical system.

(Axis Adjustment Method of Irradiation Light Using a Jig)

The present invention is characterized by an irradiation mechanism of alight or a laser of the first embodiment which is used when performingimaging or an inspection and a method of using light or a laser of thesecond embodiment for use in adjustment. The light or laser of thesecond embodiment may also be used for adjustment. At this time, thelight of the second embodiment is included in a lens or column and anirradiation location is fixed, the irradiation location is measured inadvance, and irradiation is positioned almost at a center location of anelectron optical system. This location is for example within + or −100μm depending on the mechanical assembly accuracy of the introductionmechanism. At this time, the size of the light or laser beam is largerthan an arrangement error, for example, about assembly accuracy+200˜2000μm, or φ1 mm (a 1×1.5 mm ellipse may also be used) in the example used.At this time, it is possible to use an introduction mechanism usingfiber or a lens. In this way, because the irradiation location isdetermined by the accuracy of the apparatus which is arranged, handlingbecomes easy and reproducibility of an arrangement location is good. Itis also very effective when using the optical introduction system of thesecond embodiment for adjustment.

Adjustment 1: used in an optical axis adjustment of an electron opticalsystem. Photoelectrons are emitted from a sample surface and are guidedto a detector by a secondary electron optical system. In this case,light of a laser surface beam is irradiated and two dimensional surfaceshape photoelectrons are emitted and guided to a detector by thesecondary optical system. The surface photoelectrons form a twodimensional photoelectron image which is magnified and projected at thedetector by the secondary optical system. At this time, a photoelectronimage is formed using the light introduction system of the secondembodiment and it is possible to calculate the optical axis centerconditions of the secondary optical system. The optical axis conditionscalculated in advance and the center location of an object lens (objectsurface location) is calculated in advance. In this way, a mark (acharacteristic pattern or faraday cup is used) is arranged at thislocation. Thereby, the object lens center location is determined. Next,the light or laser introduction system of the first embodiment isadjusted so that a beam is irradiated at the location of this mark. Atthis time, a structure of a mirror, lens and light source is adoptedwhereby adjustment of the irradiation location and size are adjustedusing two or mirrors and lenses. Light or laser of the second embodimentmay be irradiated at the mark at the object lens center calculated inthe first embodiment. It is possible to efficiently adjust the opticalaxis of a light or laser introduction system of the first embodimentusing this mark. If there is no secondary optical system, optical axisadjustment must be performed in the first optical introduction systemafter assembling the first optical system and therefore the location ofthe center of the object lens must be initially searched while it isstill unclear. That is, a situation where a photoelectron image can beroughly seen is formed, the secondary optical system is adjusted, thatis, the center location of an object lens is calculated while in thisstate, a mark is arranged at this location, and then optical axisadjustment of the first optical introduction system is performed. As aresult, extraction of a center of an object lens from this roughsituation and a rough optical axis adjustment of the opticalintroduction system of the first embodiment must be performedalternately while performing final axis adjustment of the secondaryoptical system and axis adjustment of the optical introduction system ofthe first embodiment. Consequently, it is effective to form a state inadvance where axis adjustment of the secondary optical system is alwayscomplete using the optical introduction system of the second embodiment.

In addition, it is possible to perform axis adjustment of a firstoptical introduction system using a jig. A power meter is arranged belowa guide plate with a hole and optical axis adjustment of the firstoptical introduction system is performed so that a maximum amount passesthrough the hole of the guide plate. At this time, the coordinates wherethe hole location of the guide plate meet the center location of theobject lens are calculated in advance.

(Light+EB Irradiation Method)

Explanation of an embodiment in the case of primary systems of two typesexist.

It is effective to form an image by combining a photoelectron imageobtained using light or laser irradiation and secondary emissionelectrons and/or mirror electrons (also includes cases where there aremirror electrons and where there are no mirror electrons). Here,secondary emission electrons refer to a partial or mixed state ofsecondary electrons, reflecting electrons or back scattered electrons.In particular, it is difficult to distinguish between these in the caseof a low LE.

An embodiment in which the light or laser in FIGS. 7˜9, FIGS. 26˜31 isirradiated to a sample is combined with an embodiment for irradiating asample using an electron beam in a primary system in FIG. 33 a˜FIG. 42.The examples of the embodiments are shown in FIG. 196, FIG. 197, FIG.198. An example whereby a sample has an uneven shape is described below.

In this example, laser (or light) irradiation and electron beamirradiation are simultaneously performed as a primary beam. As anirradiation method, it is possible to perform irradiation simultaneouslyor alternately. At this time, the characteristics of performing laserirradiation and electron beam irradiation are described below and theeffects where these are combined are also described.

By combining a photoelectron image and a secondary emission electronimage in the case of a white signal where there is a large amount ofphotoelectrons in a top layer (bump part) when performing laserirradiation, and a white signal where there is a large amount ofsecondary emission electrons in a top layer when performing irradiationusing an electron beam, the amount of electrons are increase in the toplayer (photoelectrons white+secondary emission electrons and/or mirrorelectrons), that is, an image can be formed where the top layer (bumppart) is white and hollow part is black and an increase in contrast andS/N is possible.

In contrast, in the case of performing an observation where a hollowpart with many photoelectrons is a white signal and a where a hollowpart of has many secondary emission electrons is a white signal, it ispossible to increase contrast and S/N of an image formed by a whitehollow part (photoelectrons+secondary emission electrons and/or mirrorelectrons white) and a black top layer (bump part) when laserirradiation and electron beam irradiation are performed simultaneously(combined). At this time, a white signal refers to a large amount ofelectrons are detected compared to other parts and brightness isrelatively high, that is, white imaging is possible.

As is shown in FIG. 33 (a), in the case of using an electron beam, anelectron beam splitter such as ExB is always required in order toseparate from a secondary beam (using a Wien filter condition forallowing the secondary beam to travel straight). Therefore, this type ofelectron beam splitter is also required in an embodiment for combiningan electron beam and laser or light beam. An example of this is shown inFIG. 196, FIG. 197, FIG. 198.

The difference between FIG. 196, FIG. 197 and FIG. 198 is as follows.FIG. 196 and FIG. 197 include a mechanism for introducing a laser (orlight) further to the sample side than an ExB. FIG. 198 includes amechanism for introducing a laser (or light) further to a detector sidethan an ExB. For example, in FIG. 196 and FIG. 197 a method is shown inwhich a lens introduction hole is arranged on a cathode lens and asample is irradiated with a laser after alignment adjustment isperformed using a mirror etc on the exterior of a chamber, and it ispossible to introduce fiber and a lens etc to the cathode lens andperform laser irradiation. In addition, FIG. 198 shows that is possibleto arrange a mirror similar to that explained in FIG. 26 within asecondary system column, introduce a laser from the exterior of thecolumn and irradiate a laser (or light) to a sample. FIG. 198 shows acase where an amount of electrons emitted from a bump part by laserirradiation and electron beam irradiation is large (white signal).However, the reverse may also be performed the same as in FIG. 196 inthe case where an amount of electrons from a hollow part is large (whitesignal).

In addition, with regards to a primary system electron beam, it is evenmore effective to use the electron beam explained in the embodimentsshown in FIGS. 35˜41. Because an electron beam with a narrow band energyand a large current is irradiated, the energy of the secondary emissionelectrons or mirror electrons which are formed also becomes narrow bandand it is possible to realize an image with few aberrations anddistortions and a high resolution. In addition, because the energy ofphotoelectrons generated by a laser irradiation have a narrower bandthan secondary emission electrons, it is possible to maintain an energynarrow band state even when combination is performed and therefore,although the amount of photoelectrons increases the energy width doesnot broaden. This is particularly effective and useful since it ispossible to be realized when increasing a laser or electron beam to beirradiated for raising throughput without deteriorating image quality.

In addition, the reverse case in also possible whereby thephotoelectrons which are white and the secondary emission electronswhich are black are combined. In this case, a combined image becomesgrey, that is, an intermediate color between white and black, andpattern resolution and contrast decreases. At this time, for example,the white signal of only a defect becomes stronger. Alternatively it isalso possible to perform an observation where black becomes stronger. Atthis time, for example, in the case of a defect which is highlysensitive to light irradiation, it is possible to form a white or blacksignal shape by an increase or decrease in the amount of photoelectrons.In addition, in the case of a defect which is highly sensitive toelectron irradiation, it is possible to form a white or black signal byan increase or decrease in the amount of secondary emission electrons.

In addition, a combination is also similarly possible in the case wherephotoelectrons are black and secondary emission electrons are white. Ina EUV mask example, it is possible to form the combination describedbelow with respect to a TaBO top layer and Ru hollow part.

(Combination of an Image Formed from Ru White/TaBO Black Photoelectronsand Secondary Emission Electrons and/or Mirror Electrons, Combination ofan Image Formed from Ru Black/TaBO White Photoelectrons and SecondaryEmission Electrons and/or Mirror Electrons)

In this way, it is possible to realize a high contrast and S/N andperform an inspection of a pattern defect and foreign materials withhigh sensitivity.

Oxide film potential stabilization is performed using light irradiationwith respect to a low LE image. The electron irradiation energy is −5eV<LE<10 eV. It is particularly effective when the material of the toplayer is an oxide film with respect to a low LE image. When the toplayer is an oxide film, the oxide film is charged to a negativepotential by a low LE electron beam irradiation which deteriorates imagequality. In addition, current density can not be increased. At thistime, irradiation is performed using a light such UV, DUV, EUV or X raysor a laser and the potential of the oxide film can be controlled. It ispossible to positively charge the oxide film when photoelectrons aregenerated by irradiating these lights. Consequently, it is possible tocontrol the potential of the oxide film to a constant by simultaneouslyor intermittently irradiating a low LE and these lights or a laser.Image quality becomes stable and even if current density is increased itis possible to form a stable image which can increase throughput.

(Photoelectron Cathode Primary System)

FIG. 37 shows an example used in a case where a reference voltage is ahigh voltage instead of GND. In this example the reference voltage is+40000V. A cylindrical shaped tube is used so that this referencevoltage is uniform within a column to produce an electric field. Thistube is given as tube 1. In addition, 40000V is applied and a referencevoltage is formed. Also, areas near a photoelectron are parallel with anequipotential line (distribution) photoelectron surface. As a result, amagnetic field lens is used as a lens and an electromagnetic aligner isused as an aligner. NA or a different aperture becomes a referencepotential and arranged in a tube structure. The tube 1 also includesanother tube 2 arranged on the exterior since a high voltage is applied.The tube 2 is set to GND and the device can be GND connected. The tube 1and tube 2 are insulated by an insulation material having a voltageresistance and a required application voltage is maintained. Althoughnot described here, the reference voltage of the primary system iscontrolled in order to set the reference voltage of the secondaryoptical system to a high voltage. Therefore, the secondary opticalsystem also has a column with a double tube structure the same as theprimary optical system. A high voltage is applied to the inner tube andthe exterior tube is set to GND. Thus voltage differential is maintainedthe same as the primary system. In addition, the tube 1 is a conductorand a resin material such as polyimide or epoxy may be coated on theexterior periphery of the tube 1. A conductive material may be furthercoated on the exterior periphery of the resin material and may be set toGND. In this way, the inner side of the resin material becomes a highvoltage reference voltage and the exterior side is set to GND so thatother GND connections and parts which can be set to GND can be combined.In addition, the tube 2 may be a conductor shield tube on this exterior.The tube 2 may be a magnetic body made from permalloy or pure iron andcan shut out an exterior magnetic field. Furthermore, the presentinvention can also be applied to embodiments 1˜25 described above andembodiments not attached with a number.

Twenty Sixth Embodiment EO Correction

An example of EO correction used in the inspection device and inspectionmethod of the present invention is explained.

A. Summary

When imaging a beam from a wafer using a TDI, the location of the waferrequires accurate positioning. However, actually, the wafer exists on anX-Y stage and because positioning is mechanically determined, several100 μm to several tens of nm and a response speed of several seconds toseveral ms are practical accuracy values.

On the other hand, since design rules are miniaturized approachingseveral tens of nm, performing an inspection of a wire having a wirewidth of several tens of nm or a via with a diameter of several tens ofnm is necessary and detection of a defect having these shapes or anelectrical defect and rubbish with a diameter of several tens of nm isnecessary. Imaging depending only on the mechanical positioningdescribed above, the order of response time and positioning accuracybecome separated from the order of design rules and imaging accuracywhich is a significant obstacle to obtaining an accurate image.

The imaging sequence is performed by combining a step (x axis) and aconstant speed scan (y axis), and the (y axis) which performscomparatively dynamic control is has a control residual error which isgenerally large and considering prevention of image distortion, agreater level of control is being demanded.

An X-Y stage which is highly accurate and has excellent responsivenessis included for solving these issues. However, an EO correction functionwas devises for realizing control accuracy and speed of a beam to animaging part which are issues that can not be solved by a stage.

A basic method includes accurately confirming the position of a wafer ona stage with a delay of within several microseconds at a sub nm order bya laser interferometer system and a bar mirror arranged on an x-y axis,a mechanical aperture is driven by an automatic control loop, andpositioning is performed while considering time delay and residual errorfrom a target position. A control residual error of a positioning resultperformed using this control is calculated from the difference between atarget position generated within a control device and an actual positionobtained by a laser interferometer system. On the other hand, a beam isguided to an imaging device via several electrodes and a correctiondeflecting electrode. A correction deflecting electrode has asensitivity in which deflection is possible of around several hundredsof μm or less or more preferably a hundred μm or less which is convertedto distance on a wafer, and two dimensional deflection of a beam to anarbitrary position is possible by applying a voltage to the electrode.After a control residual error is calculated by a calculation device, itis converted to a voltage using a D/A convertor, and applied to thecorrection deflecting electrode for cancelling the control residualerror. It is possible to perform correction close to the resolution of alaser interferometer using this structure.

A method in which the above procedure is used for the X axis (stepdirection) and synchronizing a transfer lock of a TDI which is animaging element with the movement speed of a stage and transferring forthe Y axis (scan direction) was also invented an alternative method.

The concept of EO correction is shown in FIG. 97. A command 95.1 isoutput to a target position and provided to a control feedback loop 95.2which includes a mechanical actuator. This part equates to a stage.Feedback is performed via a position detector 95.3 as a result of aposition displacement which is driven and the position displacement of adrive system gradually converges to the target position from theposition command, however, a residual error is produced due to thebenefit limits of the control system. The actual position is detectedwith an order of sub nm by a position output system 95.4 (the laserinterferometer is used here), a difference with the position commanddevice 95.1 is detected by a residual error detector 95.5, then appliedto a deflector electrode 95.7 using a high voltage high speed amplifier95.6, a voltage is applied to cancel the residual error. In the casewhere this function is not present, a function such as 95.9 is includedfor reducing a variation which is produced as in 95.8.

A detailed apparatus structure is shown in FIG. 98. An X-Y stage 96.1can be provided with smooth servo characteristics by driving an X axisusing a servomotor 96.2 for an X axis drive and encoder 96.3 anddetecting a rough position and speed. A servomotor is used in thepresent example, however, a similar structure in an actuator such as alinear motor or ultrasound motor is possible. 96.6 is an outputamplifier which drives a motor. Accurate position data of an X axis canrealize a position detection function which includes sub nm a resolutionby combining a mirror 96.7, interferometer 96.8, receiver 96.9, lasersource 96.10, and interferometer board 96.11.

Each function related to the X axis described above are the samefunctions for the intersecting Y direction and are realized by aservomotor 96.12, an amplifier 96.13, a mirror 96.14, an interferometer9.5, and a receiver 96.16 An X-Y stage controller 96.17 performs overallcontrol of these devices and thereby it is possible to two dimensionallyoperate a stage and realize capabilities with an accuracy of 1000 μm to1 nm, or preferably 100 μm to 2 nm and more preferably 1 μm to 2 nm andeven more preferably 0.1 μm to 2 nm and a response speed of severalthousands of ms or less, or more preferably several tens of ms or lessand even more preferably several ms or less. On the other hand, an Xreference value and Y reference value are output from X-Y stagecontroller 96.17 to an EO corrector 96.18, position data output in 32bit binary form from the interferometer 96.11 passes a high speed bufferboard 96.19 and an actual position is received by an EO corrector 96.18.After an internal calculation is performed, and after voltageamplification by high voltage high speed amplifiers 96.20, 96.21, avoltage is applied to deflection electrodes 96.22 and deflection forcorrecting a residual error part is performed and an image data electronbeam in which a position misalignment is minimized is guided to a TDI96.23 (imaging element). TDI 96.23 is a part for generating a timingsignal for determining a transfer speed of 26 described below.

A function for generating a target position in a scan direction in thepresent device is described next. EO correction is a function forcorrecting a position by calculating a difference between a targetposition and actual position and deflecting an electron beam in order tocancel this difference. However, the correction range is limited to arange of several tens of μm. This electrode sensitivity is determined bya dynamic range, noise level, the number of bits of D/A converter of ahigh voltage high speed amplifier. However, a significant misalignmentbetween the actual position of a stage when scanning with respect to thetarget position is produced compared to when stationary due to the gainof a control loop being limited. A divergence from the target positionis around 400 μm in the case of travelling at 20 mm/s, and even if thedifference is calculated and output as it is, the correction range issignificantly exceeded which saturates the system. In order to preventthis phenomenon and avoid this problem, the following procedure inperformed in the present device. This concept is shown in FIG. 99.

97.11 is a target position on a stage which moves at a constant speedduring a scan and therefore increases in a direction line with time. Onthe other hand, a mechanical position 97.2 of a stage as a result ofactual control includes a mechanical vibration of several microns and astationary deviation 97.3 of around 400 μm. While it is possible tosmooth position data when actually travelling using a filter as a meansfor removing this stationary deviation, a delay is always produced dueto a time constant of a filter, and when a time constant in which aripple (voltage variation which becomes noise) can be ignored isprovided, a measurement start area is significantly limited which leadsto a significant increase in the total amount of measurement time. Thus,in the present invention, at least the following calculation isperformed in order to detect the stationary deviation. A differencebetween the actual position and target position at the time of theprevious scan is calculated by accumulating at least 2 to the 16th powerthe number of samples. An average value 97.4 of the stationary deviationbetween the target position and the actual position is calculated bydividing this accumulation result by the number of samples. The combinedtarget position 97.6 is calculated by subtracting the average value 97.4of the stationary deviation from the target position 97.5 at the time ofa present scan. In this way, a structure is realized in which EOcorrection within a dynamic range such as the EO correction value 98.1shown in FIG. 100 is possible. Furthermore, since a desired accuracy maybe obtained the number of accumulation may be fewer the value shownhere.

A block view is shown in FIG. 101. A target value 99.1 is subtractedfrom the actual position 99.2 and the previous accumulation is performedwithin the block 99.3 at the time of a scan. On the other hand, anaverage value of a stationary deviation calculated the same as theprevious time in 99.3 is output from 99.4. EO correction data with noresponse delay or ripple is realized by a combined target position 99.6calculated by subtracting 99.4 from 99.1 using a subtractor 99.5 andsubtracting this value and the actual position 99.77 from aninterferometer.

The structure of a block difference average detection 99.3 in FIG. 101is shown in FIG. 102. A calculation is performed in 100.1, 100.2, a wordof a data selector 100.4 is selected by the value of an accumulationcounter 100.3, a division quality calculation is performed and anaverage value of a stationary deviation is output.

The idea of a transfer clock of a TDI shown in FIG. 103 is described. ATDI is an imaging element which aims to improve sensitivity and reducerandom noise by connecting several photoelectron elements in stacks in ascan direction and transferring the charge of each imaging element to afollowing element. However, as is shown in FIG. 101, it is importantthat the imaging object on a stage and a pixel on the TDI correspond oneto one and when this relationship is broken, image distortions occur. InFIG. 101, the relationship between 1-1 and 1-2 and the relationshipbetween 2-1 and 2-2 show the case where each are in a synchronizedrelationship respectively, and the relationship between 3-1 and 3-2 andthe relationship between 4-1 and 4-2 show the case where synchronizationof is misaligned respectively. TDI transfer is synchronized with anexternal pulse and transferred to the next stage, thereby when a stageis moved one pixel at a time, this can be realized when a transfer pulseis generated.

However, since the position data output of a currently mainstream laserinterferometer is in a form which synchronizes a 32 bit binary outputwith 10 MHz internal block and outputs, it is not easy to realize as itis. In addition, the accuracy of a transfer pulse is also importantgiven a resolution of several nm, and high speed highly accurate digitalprocessing is required. The method invented in the present example isshown in FIG. 104. Information data of a laser interferometer and a 10Msynchronized signal are introduced to this circuit by a buffer 102.1.The 10M clock 102.2 generates a 100 MHz clock synchronized by PLL 102.3,and is supplied to each circuit. A calculation process is performed eachtime this synchronization signal 102.4 generates a 10 state. The actualposition data is held in 102.5 and the previous value is held in 102.6.The difference between these two is calculated by 102.7, and theposition difference for each 10 start is output from 102.8. Thisdifference value is loaded as a parallel value to a parallel serialconvertor 102.9, synchronized with a 100 MHz clock and the difference isoutput as the number of serial pulses from 102.10. 102.11 also has thesame function, however, a structure where operation is possible withoutrest at each 10 state is possible by combining 102.12, 102.13. As aresult, a serial pulse corresponding to a position difference is outputfor each 10 MHz to a counter 102.14 by a summation circuit 102.10. If acomparator 102.15 is set in advance when the resolution of the laserinterferometer is 0.6 nm and 1 pixel is 48 nm, the counter outputs apulse 19 at a timing equivalent to 1 pixel. An operation synchronizedwith the variation in speed of a stage is possible by changing thissignal into an external pulse from a TDI and it is possible to preventdistortions or blurring.

A timing chart is shown in FIG. 105. 1 is interferometer coordinate(position) data and the numerals are shown as examples of a position. 2is a 100 MHz synchronized signal created by PLL. Bank A is an operationtiming of a parallel serial converter 102.9 and bank B is 102.11. Adifference calculation timing 8 is performed after a latch timing 7 forstoring position data, a value is loaded to the parallel serialconverter 102.9, and 4 is output using a 1 cycle pulse of the next 10Mclock 3. Bank B performs the same operation at a timing delayed by 1cycle of the 10M clock 3, and pulse generation 6 is easily realized.Furthermore, the present embodiment can also be applied to embodiments1˜26 described above and also to embodiments with no number attached.

Twenty Seventh Embodiment

A foreign material attachment prevention method and electron beaminspection device

A foreign material (particle) attachment prevention method in theinspection device and inspection method of the present invention isexplained.

The present embodiment of the present invention is explained in detailbelow while referring to the diagrams (FIG. 106 and FIG. 107). In theexample below, foreign materials such as particles are prevented frombeing attached to a sample surface using a rectangular mask or circularsemiconductor wafer including a thin film, for example, Si (includingdopants), Cr, TaN, TaBN, CrM, Ru, Ta, W or Cu etc on a surface layer asa sample. The uppermost layer of the thin film may be an insulation filmof TaBO, TaO or SiO₂ etc. A material on which a thin film formed on asilica or quartz substrate or a circuit pattern thin film structure foran LSI formed on a Si wafer may be used for a mask. Furthermore, in eachexample described below, the same reference symbols are attached to thesame or equivalent parts and thus overlapping explanations are omittedhere.

FIG. 106 is a longitudinal front elevation diagram which shows a summaryof the main parts of an electron beam inspection device of theembodiments of the present invention. FIG. 107 is a lateral plane viewof FIG. 106. As is shown in FIG. 106 and FIG. 107, a vacuum chamber 12which can exhaust a vacuum is arranged in an electron beam inspectiondevice 10, and an X-Y stage 14 movable in an X direction and Y directionis arranged within the vacuum chamber 12. In addition, a holder 18 whichsupports a sample 16 comprised from a rectangular mask is arranged viaan electrostatic chuck 20 on the upper surface of the X-Y stage 14.

The X-Y stage 14 includes a movement region of a stroke of effectivedistance+entrance distance (inspection maximum speed*speed stabilizationtime) so that imaging of an effective region and defect inspection of asample 16 (mask) is possible. For example, the X-Y stage 14 includes a400 mm stroke movement region when the entrance distance is 100 mm/c×0.5s=50 mm at an effective distance of 300 mm of the sample 16 in an Xdirection and Y direction.

A dust collecting electrode 22 which has a cross sectional rectangularshape and extends continuously in a rectangular frame shape is arrangedat a location which encloses the entire periphery of the sample 16separated by a predetermined interval from the sample 16 arranged on theX-Y stage 14. Furthermore, a gap control plate 24 which includes athrough hole 24 a at a center and is arranged on the upper side of thesample 16 (mask) arranged on the X-Y stage 14 and the dust collector 22,is arranged parallel with an internal periphery surface of the vacuumchamber 12 with a small gap therebetween. An optical system main element26 of the electron beam inspection device is located within the throughhole 24 a, and an electron beam is irradiated through the optical systemmain element 26 onto a surface of the sample 16 arranged on the X-Ystage 14. The size of the through hole 24 a is set to a slightly largersize than the exterior shape of the optical system main element 26.

The dust collector 22 is formed by a non-magnetic material such asphosphor bronze or Ti etc in order to prevent bending or a change in thetrajectory of an electron beam due to a magnetic field. The electronbeam includes an irradiation electron beam of a primary system, asecondary emission electron beam and a mirror electron beam reflectednear the sample 16 which are emitted from the sample 16.

The gap control plate 24 is formed from a flat plate with a thickness of0.3˜5 mm for example from a material such as phosphor bronze, Ti or SUSmaterial etc. A material coated with Au, Pt, Ru or Os etc is used as thegap control plate 24 in order to stabilize a potential or preventcontamination. In addition, the gap control plate 24 is set to a size tocover a region in which the dust collector does not extend to theexterior of a gap control plate 21 even when the X-Y stage 14 moveswithin a movement region. In this way, the X-Y stage 14 moves and whenthe sample 16 arranged on the X-Y stage 14 moves to the most slantedlocation within the vacuum chamber 12, an electric field distributionbreaks up, the trajectory of particles is prevented from changing and itis possible to prevent the attachment of particles which fly to thesurface of the sample 16. Furthermore, the gap control plate 24 is notalways necessary. This is also the case for each example describedbelow.

In this example, as is shown in FIG. 107, the dust collector 22 whichcontinues in a rectangular frame shape encloses as one unit the entireperiphery of the sample 16 which is arranged on the X-Y stage 14, and agap is produced at a location along the length direction of the dustcollector 22, parts with a non-uniform electrical field are generated,and particles are prevented from entering the interior which is enclosedby the dust collector 22 from so called gaps in the electric field.

The dust collector 22 does not always enclose the entire periphery ofthe sample 16, it is sufficient that the electric field formed by thedust collector be able to enclose the periphery of the sample 16. Forexample, as is shown in FIG. 108, the dust collector 22 which extends ina straight line shape is arranged so that it extends almost the entirelength of each side of the sample 16, and may be arranged to enclosealmost the entire exterior periphery of the sample 16. In addition,although not shown in the diagram, the dust collector electrodes whichextend in a straight line may be alternately separated midway. In thiscase, distortion in the electric field occurs between adjacent dustcollector electrodes, however, it is sufficient that a distribution of arequired potential be obtained by the dust collector electrodes. Forexample, thinking in a two dimensional manner, when the width of a dustcollector is given as D, and the distance between electrodes of the dustcollector electrodes given as L, then as long as D/L≧4 there is noproblem. This is also the same for each example described below.

In the example described above, a rectangular mask is used as the sample16. When a circular semiconductor wafer is used as the sample 16 a, asis shown in FIG. 109, the sample (semiconductor wafer) 16 a which issupported by a circular holder 18 a is arranged on the X-Y stage 14, andby arranging the dust collector electrodes 22 b which continues in acircular ring shape around the periphery of the sample 16 a, it ispossible to enclose the entire periphery of the sample 16 a as oneintegrated unit. In this case, as is shown in FIG. 110, a pair ofsemicircular dust collector electrodes 22 c is arranged to mutuallyoppose each other to form a full circle, and enclose almost the entireperiphery of the sample 16 a (semiconductor wafer) arranged on the X-Ystage 14. In addition, although not shown in the diagram, a plurality ofdust collector electrodes may be arranged separated from each otherextending along a circular periphery direction.

FIG. 111 shows an expanded view of the sample 16, dust collectorelectrodes 22 and gap control plate 24. As is shown in FIG. 111, a firstpower source 28 which applies a predetermined voltage to the surface ofthe sample 16 is connected to the sample 16, and a second power source30 which applies predetermined voltage to the dust collector electrode22 is connected to the duct collector electrode 22. The thickness of thedust collector 22 is 0.1˜5 mm for example. The wider a width W1 of thedust collector electrode 22 the better, although the wider this widthbecomes, the size occupied by the dust collector electrode 22 inside thevacuum chamber 12 increases and therefore generally 5˜50 mm ispreferred. The distance L1 between the sample 16 and the dust electrode22 is preferred to be in a range which satisfies the relationship withthe width W1 of the dust collector electrode 22 which is 0.5L1<W1<5L1for example.

In this example, a voltage of −1˜−5 kV is applied through the firstpower source 28 to the surface of the sample 16, and a large voltagehaving an more absolute value than the voltage applied to the sample 16,for example, 0.5˜5 kV is applied through the second power source 30 tothe sample 16 with the same polarity as a voltage applied to the sample16. That is, for example, when a voltage of −3 kV is applied to thesample 16, a voltage of −3.5˜8 kV, for example, −5 kV is applied to thedust collector electrode 22.

The vacuum chamber 12 is set to an earth potential and manufactured froma metal material such as iron or aluminum. In addition, when a foreignmaterial such as particle which exists with the vacuum chamber 12 ischarged by static electricity etc, in the case where the potential ofthe sample 16 is negative, foreign materials such as a positivelycharged particle are attracted by an electric field and fly towards thesample 16.

According to this example, by enclosing the entire periphery of thesample 16 which is applied with a negative potential with the dustcollector electrode 22 and applying a larger negative voltage than thevoltage applied to the sample 16 to the dust collector electrode 22, themajority of foreign materials such as particles which are attracted byan electric field are captured by a dust collector electrode 18 and itis possible to significantly reduce the possibility of foreign materialssuch as particles from attaching to the surface of the sample 16. Inthis way, it is possible to prevent foreign materials from beingattached to the surface of the sample 16.

In this example, a gap control plate 24 which prevents the attachment offoreign materials such as particles to the surface of the sample 16after following a trajectory away from the dust collector electrode 22is arranged. In this way, when the gap control plate 24 is arranged, thesuction power of the dust collector electrode 22 towards foreignmaterials such as particles which pass a trajectory away from the dustcollector electrode 22 decreases, and thereby the possibility of foreignmaterials such as particles being captured by the dust collectorelectrode 22 decrease in proportion to distance. As a result, when anegative voltage is applied to the sample 16, by making sure theelectric field strength A between the sample 16 and the dust collectorelectrode 22 becomes negative (A<0), it is possible to increase thesuction power of the dust collector electrode 22 and increase thepossibility of foreign materials such as particles being captured by thedust collector electrode 22. In addition, by ensuring that electricfield strength B (absolute value) between the gap control plate 24 andthe dust collector electrode 22 has the relationship 0.1≦B (absolutevalue)≦10 kV/mm, it is possible to increase the possibility of foreignmaterials such as particles being captured by the dust collectorelectrode 22.

For example, a negative voltage of −1˜−5 kV is applied to the sample 16,and a large negative voltage of −5˜−10 kV which is −0.5˜−5 kV largerthan the negative voltage applied to the sample 16 is applied to thedust collector electrode 22. When the gap control plate 24 is set to anearth potential, the distance between the sample 16 and the dustcollector electrode 22 is L1=10 mm, and the distance between the gapcontrol plate 24 and the dust collector electrode 22 is Z1=8 mm, theelectric field strength A between the sample 16 and the dust collectorelectrode 22 becomes negative (A<0), and the electric field strength(absolute value) between the gap control plate 24 and the dust collectorelectrode 22 becomes B=0.19˜1.25 kV/mm (=1.5˜10 kV/8 mm), and inparticular, when a voltage of −5 kV is applied to the dust collectorelectrode 22, the electric field strength (absolute value) becomesB=0.625 kV/mm (=5 kV/8 mm), which is an effective condition. At thistime, it is possible to prevent electrical discharge in space occurringby making sure the voltage resistance of space does not exceed 10 kV/mm.

FIG. 112 shows the details of the X-Y stage 14. As is shown in FIG. 112the X-Y stage 14 is formed by alternately stacking an X stage 32 and Ystage 34 and an ultrasound motor 36 is arranged between the X stage 32and Y stage 34. In addition, an upper end of a first dust control cover40 which reaches the upper side of the dust collector electrode 22, isarranged at a location which encloses the exterior side of the dustcollector electrode 22 on the upper surface of the X-Y stage 14, and asecond dust control cover 42 which blocks off an aperture end of ahousing part of the ultrasound motor is arranged on the exterior side ofthe ultrasound motor 36.

In this way, it is possible to prevent foreign materials such asparticles heading towards the sample 16 from attaching to the surface ofthe sample 16 by arranged the first dust control cover 40. In addition,it is also possible to prevent foreign materials such as particlesflying from the ultrasound motor 36 from flying into the vacuum chamber12 by arranging the second dust control cover 42 on the exterior side ofthe ultrasound motor 36 which is a source of particles. In this way,preventing foreign materials such as particles flying from a particlesource into the vacuum chamber 12 is particularly effective in the caseof using a motor which is driven by friction with a side surface of apiezo actuator etc.

In this example, as is shown in detail in FIG. 113, a sealed structurewire box 50 is arranged within the vacuum chamber 12. The wire box 50 isfor preventing foreign materials such as particles which are generatedfrom a cable by bending or friction of the cable from flying into thevacuum chamber 12. In this example, all the parts of a cable 52 whichbends with the movement of the X-Y stage 14 are enclosed within the wirebox 50. That is, one end of the cable 52 extends in a straight linetowards the wire box 50 from the X-Y stage 14, passes through a slit 50a arranged on the wire box 50, reaches the inside of the wire box 50 andcurves and is inverted 180° towards the bottom. In addition, the otherend of the cable 52 is connected to a movement plate 58 which isarranged on a terminal base 56 b arranged within the wire box 50. Inthis way, when the X-Y stage 14 moves in an X direction, only a curvedpart 52 a of the cable 52 within the wire box 50 curves.

A guide roller 60 which acts as guide of the cable 52 and extends alonga Y direction is arranged within the wire box 50, and when the X-Y stage14 moves in a Y direction, the movement plate 58 moves in a Y directionalong the guide roller 60 and thus stress in a Y direction is notapplied to the cable 52 up to the movement plate 58. Although not shownin the diagram, a cable which extends from the terminal base 56, passesthrough a wire hole arranged in the wire box 50 and connects to a feedthrough which is arranged in the vacuum chamber 12.

In this way, when all of the curved parts of the cable 52 are within thewire box 50, it is possible to significantly reduce the possibility offoreign materials such as particles generated within the wire box 50from escaping to the exterior of the wire box 50 because a hole whichpasses through to the exterior of the wire box 50 is small, and themajority of these particles become attached to an inner wall of the wirebox 50. Furthermore, in this example, by arranging a wire box dustcollector electrode 62 within the wire box 50 and applying a voltage forcapturing foreign materials such as particles to the wire box dustcollector electrode 62, it is possible to significantly reduce thepossibility of foreign materials such as particles from flying from thewire box 50 to the exterior.

Furthermore, by applying measures such as 1) aligning the length ofcables 2) correcting cables by fixing a cable tie (tie band) and 3)using a flat cable, it is possible to reduce the generation of particlesdue to friction between a plurality of cables. That is, when the lengthsof a plurality of cables are aligned and fixed, a cable bunch isintegrated but bends when the X-Y stage moves.

However, by reducing friction between each of these cables it ispossible to reduce the generation of foreign materials such asparticles. In addition, by using a flat cable, it is possible to turn aplurality of wires into one cable and remove friction between cables.Furthermore, when a flat cable having a plurality of wire can not beused immediately it is possible to combine 1) and 2) described above.

In the example described above, a lateral profile rectangular shapeddust collector electrode 22 was used. However, as is shown in FIG. 114,a lateral profile circular dust collector electrode 22 may also be used.The diameter D of the dust collector electrode 22 is preferably within arange which satisfies the relationship 5L2<D<5L2 for example with therelationship distance L2 between the sample 16 and the dust collectorelectrode 22 d. When the diameter D of the dust collector electrode 22 dis smaller than this, the capturing possibility of the dust collectorelectrode 22 d decreases, and in the case where D is larger than this,the capturing possibility of the dust collector electrode 22 d does notchange, rather it attracts the capture of excessive foreign materialssuch as particles.

In addition, in the example described above, the dust collectorelectrode 22 is arranged at a location separated by a predeterminedinterval from the sample 16, and a voltage with a larger absolute valuethan the voltage applied to the sample 16 with the same polarity as thevoltage applied to the sample 16 is applied to the dust collectorelectrode 22. However, as is shown in FIG. 115, it is possible toarrange a lateral profile rectangular shaped dust collector electrode 22e which continues in a rectangular frame shape so as to contact theinterior periphery edge part to the exterior periphery edge part of thesample 16 and enclose the entire periphery of the sample 16, and applythe same voltage as the voltage applied to the sample 16 via a firstpower source 28 to the dust collector electrode 22 e via the secondpower source. The thickness of the dust collector electrode 22 e is forexample 0.1˜5 mm and the width W2 may be the same as the dust collectorelectrode 22 previously described, for example, 5˜50 mm.

In the example above, a dust collector electrode 22 e which includes aninterior shape which is smaller than the exterior shape of the sample 16and the interior periphery edge part of the dust collector electrode 22e is made to contact the exterior periphery edge part of the sample 16.However, as is shown in FIG. 116, for example, it is possible to use adust collector electrode 22 f which has a rectangular frame shape and aslightly larger interior shape than the exterior shape of the sample 16,and arranged the dust collector electrode 22 f so that it encloses theentire periphery of the sample 16 with a small gap S arrangedtherebetween. This gap S is for example 1˜500 μm.

In the example described above, for example, a −1˜−5 kV negative voltageis applied via a first power source 28 to the sample 16, and when avoltage the same as the voltage applied to the sample 16 via the secondpower source 30 is also applied to the dust collector electrode 22 e,for example when −3 kV is applied to the sample 16, the voltage appliedto the dust collector electrode 22 e is −3 kV.

As stated previously, when the potential of the sample 16 is negative,foreign materials such as particles which are positively charged areattracted by an electric field, and fly towards the sample 16. Accordingto this example, when the dust collector electrode 22 e which is thesame potential as the sample 16 is arranged at a location which enclosesthe entire periphery of the sample 16, the majority of foreign materialssuch as particles which are attracted by the electric field, arecaptured by the dust collector electrode 22 e. In this way, by capturinga majority of foreign materials such as particles using the dustcollector electrode 22 e which is arranged on the periphery of thesample 16, it is possible to reduce the amount of foreign materials suchas particle which fly towards and become attached to a sample 16surface, and in this way it is possible to prevent foreign materialsfrom becoming attached to the surface of the sample 16.

In the example described above, when the distance between the dustcollector electrode 22 e and the gap control plate 24 is given as Z2,and given the relationship with the width W2 of dust collector electrode22 e, it is particularly effective when W2>4Z2. In addition, when thesize (absolute value) of a voltage density B between the dust collectorelectrode 22 e and the gap control plate 24 is increase more than 0.1kV/mm, it is more effective when (B(absolute value)>0.1 kV/mm).

FIG. 117 shows another example which combines the example which ismainly shown in FIG. 111 and the example shown in FIG. 115. In thisexample, a first dust collector electrode 70 is arranged which contactsan interior periphery edge part with an exterior periphery edge part ofthe sample 16, and has a lateral profile rectangular shape whichcontinues in a rectangular frame shape so as to enclose the entireperiphery of the sample 16, and a second dust collector electrode 72 isarranged which has a lateral profile rectangular shape which continuesin a rectangular frame shape so as to enclose the entire periphery ofthe first dust collector electrode 70. In addition, a second powersource 74 is connected to first dust collector electrode 70 and a thirdpower source 76 is connected to the second dust collector electrode 72.

Furthermore, as stated previously, the second dust collector electrodewhich extends in a straight line is arranged to extend along almost theentire length of each side of the first dust collector electrode, andthe second dust collector electrode may be arranged so as to enclosealmost the entire exterior periphery of the first dust collectorelectrode or the second dust collector electrode which extends in astraight line may be arranged to be separate from the first dustcollector electrode at a midway point.

In this example, as stated previously, for example, a −1˜−5 kV voltageis applied to the sample 16 via the first power source 28, and when avoltage the same as the voltage applied to the sample 16, for example is−3 eV, the voltage applied to the first dust collector electrode 70 is−3 eV. Furthermore, a larger voltage having an absolute value, forexample, 0.5˜5 kV, than the voltage applied to the sample 16 with thesame polarity as the voltage applied to the sample 16 is applied to thesecond dust collector electrode 72. That is, for example, when a −3 kVvoltage is applied to the sample 16, −3.5˜−8 kV, for example, a −5 kVvoltage is applied to the second dust collector electrode 72.

In this example also, almost the same as the example shown in FIG. 111etc described above, when a negative voltage is applied to the sample16, by ensuring that the electric field strength A between the sample 16and the second dust collector electrode 72 becomes negative (A<0), thesuction power of the second dust collector electrode 72 is increased,and the possibility of the second dust collector electrode 72 capturingforeign materials such as particles is increased. Furthermore, byensuring that the electric field strength (absolute value) B between thegap control plate 24 and the second dust collector electrode 72 has therelationship 0.1≦B (absolute value)≦10 kV/mm, it is possible to furtherincrease the possibility of the second dust collector electrode 72capturing foreign materials such as particles.

The first dust collector electrode 70 has a thickness, for example of0.1˜5 mm and a width W3 of 5˜50 mm the same as the dust collectorelectrode 22 e shown in FIG. 115 described above. In addition, thesecond dust collector electrode 72 has a thickness, for example of0.1˜50 mm and a width W4 of 5˜50 mm the same as the dust collectorelectrode 22 shown in FIG. 111 described above.

In addition, for example, a negative voltage −1˜−5 kV is applied to thesample 16 and the first dust collector electrode 70, and a negativevoltage of −1.5˜10 kV which is −0.5˜5 kV larger than the negativevoltage applied to the sample 16 and first dust collector electrode 70,is applied to the second dust collector electrode 72. When the gapcontrol plate 24 is set to an earth potential and when the distance Zbetween the gap control plate 24 and the second dust collector electrode72 is given as Z8=8 mm, the electric field strength A between the sample16 and the second dust collector electrode 72 becomes negative (A<0),and the electric field strength (absolute value) between the gap controlplate 24 and the second dust collector electrode 72 becomes B=0.19˜1.25kV/mm (=1.5˜10 kV/8 mm), and in particular, when a −5 kv voltage isapplied to the dust collector electrode 22, the electric field strength(absolute value) becomes B=0.625 kV/mm (=5 kV/8 mm) which is aneffective condition. At this time, by ensuring that a space voltageresistance does not exceed 10 kV/mm, it is possible to prevent electricdischarge of a space.

FIG. 118 is a concept view which shows another embodiment of an electronbeam inspection device. In this example, a projection type opticalinspection device 80, SEM type inspection device 82 and opticalmicroscope 84 are arranged in a vacuum chamber 12 which is arranged withan X-Y stage 14 in its interior, the X-Y stage 14 having a sample 16,and an observation and inspection can be performed on the sample 16arranged on the X-Y stage 14 within the vacuum chamber 12 using both theprojection type optical inspection device 80 and SEM type inspectiondevice 82.

According to this example, because the sample 16 is mounted on the X-Ystage 14 which is common to both the projection type optical inspectiondevice 80 and SEM type inspection device 82, when the sample movesbetween the projection type optical inspection device 80 and SEM typeinspection device 82, a coordinate relationship is unambiguouslycalculated and it is possible to easily and accurately specify the samepotential.

That is, when a sample moves between separated devices, it is necessaryto arrange a sample on separate stages, and therefore it is necessary toalign the sample on each stage which results in a specification error of5˜10 μm or more for the same place. In particular, in the case where asample does not include a pattern, a location reference can not bespecified and therefore this error is further increased,

According to this example, because it is possible to specify the sameplace with a high level of accuracy even when a sample 16 is movedbetween the projection type optical inspection device 80 and SEM typeinspection device 82, specification of a place can be performed with anaccuracy of 1 μm or less for example. In this way, when an inspection ofa pattern and pattern defect is performed using the projection typeoptical inspection device 80, it is effective to perform a specificationand detailed observation (review) of the detected defect using the SEMtype inspection device 82. That is, because a place can be specified itis possible to not only determine the present of a defect (or detectionof a false defect) but also accurately and rapidly determine the shapeand size of the defect. When there are separate devices, a large amountof time is waster on a pattern defect and its specification.

As described herein, while preventing the attachment of foreignmaterials such as particles to a surface of the sample 16, by using adevice system in which the projection type optical inspection device andSEM type inspection device are mounted within the same chamber, inparticular, it is possible to perform an inspection, specification andclassification of an ultrafine pattern of 100 nm of less efficiently andrapidly.

As is shown in FIG. 119, even if a particles comprised form aninsulation material exists within a uniform electric field (q₊=q⁻)between electrodes comprised from parallel plates, although the particleis polarized due to electrostatic induction from the electric field itdoes not fly. However, when the electric field is a non-uniform electricfield, the particles fly due to a charge produced by inducedpolarization. Similarly, as is shown in FIG. 120, when a particlecomprised form an insulation material exists in a non-uniform electricfield (q₊≠q⁻) between a pair of electrodes where one is a plate, theparticle is polarized due to electrostatic induction from the electricfield and flies. However, as is shown in FIG. 121, when a particlecomprised form an insulation material exists in a uniform electric field(q₊=q⁻) between a pair of electrodes where one is a plate, although theparticle is polarized due to electrostatic induction from the electricfield it does not fly.

That is, as is shown in FIG. 120 and FIG. 121, it is considered that thepossibility that a foreign material such as a particle will fly iscontrolled to the initial charge q₀ of a particle controlled before theforeign material such as a particle is induced polarization. The initialcharge q₀ held by a residual substance is thought to be provided withstatic electricity produced by the flow of air mainly during a vacuumdischarge.

FIG. 122 shows another vacuum chamber 12 a arranged in an electron beaminspection device. An X-Y stage 14 arranged with a sample 16 is arrangedwithin the vacuum chamber 12 a. Two vacuum pumps 90 a, 90 b areconnected to the vacuum chamber 12 a, and a common dry pump 92 isconnected to the two vacuum pumps 90 a, 90 b. In addition, a gas isionized using a soft X ray or UV ray in order not to charge foreignmaterials (residual materials) such as particles which can not beremoved by cleaning the vacuum chamber 12 a, and a neutralization device94 for removing static electricity on the surface of a substance withinan ionized gas by the ionized gas is arranged.

According to the present example, the neutralization device 94 isoperated at the same time as when a vacuum discharge begins within thevacuum chamber or before a vacuum exhaust begins, and the neutralizationdevice 94 is continuously operated during the vacuum discharge processwhich is performed with the vacuum chamber 12 a. That is, the flow ofwithin the vacuum chamber 12 a is removed, and the neutralization device94 is continuously operated until static electricity is no longergenerated by the flow or air. In this way, by preventing charging of aforeign material (residual material) such as particles within the vacuumchamber 12 a and when this initial charge is given as q₀=0 (refer toFIG. 121), it is possible to reduce the possibility of flying caused byinduction polarization due to a non-uniform electric field.

In addition, even if foreign materials such as particles which remainwithin a vacuum chamber since they can not be removed by cleaning areultrafine and few, they are deposited on the surface of a planar surfacestructure within the vacuum chamber due to gravity.

FIG. 123 is a perspective view which shows one example of a wall whichforms a planar structure of the vacuum chamber shown in FIG. 106 forexample or the vacuum chamber 12 a shown in Fig, FIG. 122, and FIG. 124is a cross section view of FIG. 123. As is shown in FIG. 123 and FIG.124, for example, a wall which forms a planar structure in the vacuumchamber 12 or 12 a (refer to FIG. 106 and FIG. 122 etc) is formed by awall unit 96 arranged with a plurality of lattice shaped holes 96 a onan inner surface. In this way, by arranging a plurality of latticeshaped holes 96 a on an inner surface of the wall unit 96, foreignmaterials P such as particles which remain within the vacuum chamber aredeposited on the bottom part of the holes 96 a due to gravity. Anelectric field does not enter to the bottom of the lattice shaped holes96 a due to an static electric shield effect of the lattice shaped holes96 a and as a result, the foreign materials (residual materials) P whichare deposited on the bottom part of the lattice shaped holes 96 a do notreceive a pulling force by static electricity and do not fly. In thisway, it is possible to prevent foreign materials such as particles whichremain within the vacuum chamber 12 or 12 a from attaching to thesurface of a sample 16 which is arranged within the vacuum chamber 12 or12 a.

FIG. 125 is a perspective view which shows another example of a wallwhich forms a planar structure of the vacuum chamber 12 shown in FIG.106, or vacuum chamber 12 a shown in FIG. 122 for example, and FIG. 126is a cross section view of FIG. 125. As is shown in FIG. 125 and FIG.126, a wall which forms a planar structure of the vacuum chamber 12 or12 a (refer to FIG. 106 and FIG. 122 etc) is formed from a plate shapedwall unit 98 and a plate 100 having a mesh structure which is laidparallel to the wall unit 98 separated by a predetermined interval, andthe mesh structured plate 100 is connected to an independent powersource 102.

In this way, for example, foreign materials P such as particles whichremain within the vacuum chamber 12 or 12 a are made to pass through themesh structure plate 100 by gravity and reach the surface of the wallunit 98. Because the wall unit 98 is covered by the mesh structure plate100, an electric field is blocked by the mesh structure plate 100, anddoes not reach the surface of the wall unit 98. As a result, foreignmaterials (residual materials) P which reach the surface of the wallunit 98 do not receive a pulling force by static electricity and do notfly. In this way, it is possible to prevent foreign materials such asparticles which remain within the vacuum chamber 12 or 12 a fromattaching to the surface of a sample 16 which is arranged within thevacuum chamber 12 or 12 a.

In particular, by being able to independently apply a voltage to themesh structured plate 100, foreign materials P such as particles whichremain within a vacuum chamber are actively attracted to the meshstructured plate 100, become interdependent with the effects of gravityof the foreign materials P and it is possible to deposit the foreignmaterials P on the surface of the wall unit 98 which forms a planarstructure of the vacuum chamber 12 or 12 a.

The present invention is not limited to the embodiments of the presentinvention explained herein. Various modifications are possible with thescope of the technical idea of the invention. Furthermore, the presentinvention can also be applied to the embodiments 1˜27 described aboveand to embodiments that are not attached with numbers.

Twenty Eighth Embodiment

Substrate mounting device which mounts a substrate on a tray and methodof positioning the substrate with respect to the tray

A substrate mounting device which mounts a substrate on a tray and amethod of positioning the substrate with respect to the tray areexplained in a method of the inspection device and inspection method ofthe present invention.

The substrate mounting device of the embodiment of the present inventionis explained below using the diagrams.

In the present embodiment, a substrate is a mask for example used in aEUV exposure device. In addition, the substrate mounting device is forexample, arranged with a substrate inspection device for a mask.

FIG. 127 and FIG. 128 show an inspection device arranged with thesubstrate mounting device. The concept of the inspection device isexplained before explaining in detail the substrate mounting device.

FIG. 127 is a diagram seen from above the inspection device 1. As isshown in FIG. 127, the inspection device 1 is largely divided into anatmosphere transfer part 3 and vacuum transfer part 5. The atmospheretransfer part 3 handles a substrate within an atmosphere and the vacuumtransfer part 5 handles a substrate within a vacuum. The atmospheretransfer part 3 and vacuum transfer part 5 are sectioned by an intervalwall which can be opened and closed.

The atmosphere transfer part 3 is called a mini-environment chamber. ASMIF pod 7 is arranged adjacent to the atmosphere transfer part 3. Inaddition, an atmosphere transfer robot 9, substrate rotation inventionunit 11, substrate mounting unit 13, neutralization unit 15 and fanfilter unit (FFU) are arranged in the atmosphere transfer part 3.

The SMIFF pod 7 is a structure for supporting a substrate (mask) beforeor after an inspection. The atmosphere transfer robot 9 is a robot whichtransfers a substrate in an atmosphere. The substrate rotation inversionunit 11 receives a substrate from the atmosphere robot 9 and can rotateand invert the substrate. The substrate mounting unit 13 mounts asubstrate onto a tray. The substrate mounting unit 13 is the substratemounting device of the present embodiment. The neutralization unit 15performs a neutralization process of a substrate before or after aninspection. The fan filter unit (FFU), although not shown in thediagram, is arranged on an upper part within the mini-environmentchamber of the atmosphere transfer part 3. Specifically, the FFU formsthe upper part of the atmosphere transfer robot 9, the substraterotation inversion unit 11, substrate mounting unit 13 andneutralization unit 14 and is arranged or near the ceiling.

In addition, a load lock chuck 17, transfer chamber 19, first turbo pump21, main chamber 23, inspection column 25 and second turbo pump 27 arearranged on the vacuum transfer part 5.

Two CCD cameras 29 are arranged in the load lock chamber 17. The CCDcameras 29 are used in positing of a substrate as described below. Thetransfer chamber 19 is a chamber for transferring a substrate to themain chamber 23 from the load lock chamber 17. The transfer chamber 19is arranged with a vacuum transfer robot 31. The vacuum transfer robot31 transfers a substrate within a vacuum. In addition, the first turbopump 21 maintains the load lock chamber 17 and the transfer chamber 19in vacuum state. The main chamber 23 and the inspection column 25 have astructure which irradiates a charged particle beam onto a substrate andinspects the substrate. The second turbo pump 27 maintains the mainchamber 23 and the inspection column 25 in a vacuum state.

FIG. 128 is a diagram seen from a side direction of the main chamber 23and the inspection column 25. The main chamber 23 is arranged with astage 33. The stage 33 is mounted with a tray which supports asubstrate. The stage 33 has a structure which moves the tray in ahorizontal direction, that is, X, Y θ directions. The X, Y directionsare along a mutually intersecting axis and the θ direction is an ablearound a rotation axis, that is, rotation movement is also performed.

The inspection column 25 is connected to the upper side of the mainchamber 23. The inspection column 25 is arranged with an electron gun35, primary lens system 37, secondary lens system 39 and detector 41.The electron gun 35 is a charged particle beam source. The electron gun35 and the primary lens system 37 are electron beam irradiation systemsand irradiate a substrate with an electron beam. The electron beam isdeflected by a Wien filter 43, passes through an object lens system 45,and is irradiated to the substrate. When an electron beam is irradiatedto a substrate, the substrate emits a signal having a substrate data.The signal is comprised of for example, secondary emission electrons(secondary electrons, reflected electrons, back scattered electrons) andmirror electrons. This signal passes through the object lens system 45,Wien filter 43, and secondary lens system 39, reaches the detector 41and is detected by the detector 41.

The detector 41 is connected to an image processing part 47 and thedetected signal is supplied to the image processing part 47. The imageprocessing part 47 has a structure formed from a computer having animage processing function and processes a defect inspection. That is,the image processing part 47 forms an image of the sample from a signaldetected by the detector 41, processes the image of the sample andperforms detection and determination of a defect.

In addition, as is shown in FIG. 128, the inspection device 1 isarranged with a control part 49. The control part 49 is a computer whichcontrols the entire inspection device 1 and carries out an inspection.The control part 49, as shown in the diagram, controls the main chamber23, the inspection column 25 and the image processing part 47. In thisway, the control part 49 moves a substrate (tray), irradiates anelectron beam onto the substrate and produces an image of the substratein the image processing part 47.

The control part 49 can control inspection conditions. Specifically, thecontrol part 49 controls the beam energy, magnification and dose amountof an electron beam. Specifically, the beam energy is the landing energywhen the electron beam is irradiated to a substrate.

In the present embodiment, the inspection device 1 is a projection typeinspection device. In a projection type inspection device an electronbeam includes a beam size (beam diameter) corresponding to a twodimensional pixel group, that is, includes a certain size. Anirradiation region on a sample also includes an area corresponding to atwo dimensional pixel group. A signal detected by a detector 41 alsocorresponds to a two dimensional pixel group. In addition, the detector41 includes a detection capability corresponding to a two dimensionalpixel group, for example, a CCD camera including a two dimensionaldetection surface.

A projection type inspection device is compare with a SEM typeinspection device. In a SEM an electron beam narrowly corresponds to onepixel. In a SEM, the electron beam is scanned, a 1 pixel measurement isrepeated, the measurement values are accumulated and a sample image isobtained. In a SEM type inspection device, an electron beam has a beamsize of 1 pixel, however, in a projection type inspection device theelectron beam has a beam size corresponding to a plurality of pixelgroups. The projection type inspection device can inspect a fineparticle. In addition, the projection type inspection device can alsoperform several types of inspection. For example, the projection typeinspection device can also be used for inspection of foreign materialssuch as particles, and can also be used in a multilayer film defectinspection.

Returning to FIG. 127, the entire operation of the inspection device 1is explained. The atmosphere transfer robot 9 extracts a substrate fromthe SMIF pod 7, and transfers it to the neutralization unit 15. Theneutralization unit 15 neutralizes the substrate. In addition, thesubstrate is transferred to the substrate rotation inversion unit 11from the atmosphere transfer robot 9, and rotation and inversion of thesubstrate is performed according to necessity. Furthermore, theatmosphere transfer robot 9 transfers the substrate to the substratemounting unit 13. In the substrate mounting unit 13, the substrate ismounted onto a tray prepared in advance.

When a substrate is mounted on a tray, the atmosphere transfer robot 9transfers the substrate to the load lock chamber 17 while supporting thetray. At this time, an interval wall between the atmosphere transferpart 3 and the vacuum transfer part 5 is opened. In the load lockchamber 17, a CCD camera 29 images a mark on the substrate. In this way,a mark location is detected. The vacuum transfer robot 31 transfers thetray from the load lock chamber 17 to the main chamber 23 and mounts thetray on the stage 33 of the main chamber 23. At this time, positing ofthe substrate is carried out based on the mark detection result.

The substrate is positioned by the substrate mounting unit 13 whenmounting to the tray. Then, when mounting on the stage 33 as describedabove, the substrate is positioned based on the detection result of theCCD camera 29. The former positioning can be called “temporarypositioning” and the later positioning can be called “actualpositioning”. In an actual substrate inspection process, furtherpositioning may be performed using an optical microscope after actualpositioning is performed. An optical microscope is arranged in theelectron beam inspection device and the main chamber 23. The substrateand the tray are positioned using an optical image of the opticalmicroscope, and from there the substrate is inspected using an electronbeam. Here, for example, the substrate is positioned so that an electronbeam is irradiated to a defect location detected by the opticalmicroscope.

An inspection is performed using electron beam irradiation in the mainchamber 23 as explained using FIG. 128. A substrate which has beeninspected is transferred to the load lock chamber 17 from the mainchamber 23 via the transfer chamber 19 by the vacuum transfer robot 31.

In addition, the atmosphere transfer robot 9 transfers the substrate tothe substrate mounting unit 13 from the load lock chamber 17. Thesubstrate is released from the tray in the substrate mounting unit 13.The substrate is transferred to the substrate rotation inversion unit11, and rotated and inverted according to necessity. Then, the substrateis transferred to the neutralization unit 15 and neutralization isperformed. In addition, the substrate is returned to the SMIFF pod 7 bythe atmosphere transfer robot 9.

The entire structure and operation of the inspection device 1 isdescribed above. The structure described above is a typical systemstructural example, and the operations described above are typicalexamples of an operation pattern. As a result, the inspection devicepart explained above may be replaced by an inspection device whichutilizes light of a primary beam and photoelectrons of a secondary beamas in FIG. 9, and the structure and operations of the inspection devicein the scope of the present invention are not limited to the examplesdescribed above.

(Substrate Mounting Device)

Next, a substrate mounting device of the present embodiment is explainedin detail. The substrate mounting device is equivalent to the substratemounting unit 13 of FIG. 127 already described and functions togetherwith the atmosphere transfer robot 9 and mounts a substrate onto a tray.The substrate may be a mask for example and more specifically may be aglass mask having a square shape with each side being 6 inches and athickness of 6.35 mm.

FIG. 129˜FIG. 138 show the substrate mounting device of the presentembodiment. FIG. 129˜FIG. 132 shows the substrate mounting device 51with no tray. FIG. 133˜FIG. 136 shows the substrate mounting device 51together with a tray. FIG. 129 is a planar view of the substratemounting device 51, FIG. 130 is a diagram of the substrate mountingdevice 51 seen from the arrow A direction, FIG. 131 is a diagram of thesubstrate mounting device 51 in FIG. 129 seen from the arrow Bdirection, FIG. 132 is a diagram of the substrate mounting device 51 inFIG. 129 seen from the arrow C direction cut along diagonal lines of thetray T and substrate S. Similarly, FIG. 133 is a planar view of thesubstrate mounting device 51, FIG. 134 is a diagram of the substratemounting device 51 in FIG. 133 seen from the arrow D direction, FIG. 135is a diagram of the substrate mounting device 51 in FIG. 133 seen fromthe arrow E direction, FIG. 136 is a diagram of the substrate mountingdevice 51 in FIG. 133 seen from the arrow F direction cut along diagonallines of the tray T and substrate S. In addition, FIG. 137 and FIG. 138are abbreviated diagrams which exemplary show the substrate mountingdevice 51 for the purposes of explanation.

The substrate mounting device 51 is a device for mounting a substrate Son a tray T. The substrate mounting device 51 is broadly formed by astage 53, a lift mechanism 55, a clamp mechanism 57, a tray supportmechanism 59 and a frame dropping mechanism 61. Below, the structure isexplained first and then each structure of the substrate mountingmechanism.

(Tray T)

The structure of the tray T is explained while referring to FIG.133˜FIG. 138. As is shown in FIG. 137 etc, the tray T is formed from atray body 71 and a frame 73. The tray T for example is made from aceramic.

The tray body 71 has a plate shape and has a roughly square shape withrespect to the square shaped substrate S. A plurality of substratemounting pins 75 protrude from the tray body 71 and the substrate S issupported by the substrate mounting pins 75. There are four substratemounting pins 75. By adopting this structure, the substrate contactswith the substrate mounting pins at a small contact area and does notdirectly contact with the tray body 71 and is thereby maintained in afloating state. In addition, the substrate mounting pins 75 include asurface which makes it difficult for the substrate S to slide and thusmisalignment of the substrate S during transfer is prevented.

The frame 73 is supported by the tray body 71 and encloses the substrateS. The frame 73 has a structure for providing a potential to the uppersurface of the substrate S during an inspection, and this potential isprovided via a terminal part 77. In addition, the frame 73 functions asa dummy by enclosing the substrate S. Bending of an equipotentialsurface at a part of the substrate S is reduced and it is possible tomake the potential near the end part uniform, thereby the potential ofthe entire substrate which includes the end part can be made uniform andinspection accuracy can be improved. In addition, the frame 73 can belifted vertically with respect to the tray body 71. As is shown in FIG.137, when the frame is lowered, the frame surface and substrate surfaceare at the same height, and the frame 73 encloses the substrate S. As isshown in FIG. 134 and FIG. 135, when the frame 73 is raised, aninsertion opening 70 is formed between the tray body 71 and the frame73. The insertion opening 79 is a gap or aperture between the tray body71 and the frame 73 and may also be called an insertion gap. Theinsertion opening 79 allows insertion or extraction of the substrate Sand allows access for positioning the substrate S.

Next, the frame 73 is explained in more detail. The frame 73 includes aframe body 81 and a plurality of frame leg parts 83 which extend belowthe frame body 81.

As is shown in FIG. 133 and FIG. 138, the frame body 81 is a squareshaped plate including a square shaped aperture 85. The material of theframe body 81 may be an insulator, for example a ceramic. The aperture85 has a size corresponding to the substrate S. The substrate S isarranged within the aperture 85 and thereby the substrate S is enclosedby the frame 73. The frame body 71 and the substrate S do not havedirect contact. An almost constant gap is formed between the entireframe body 81 and the substrate S.

A frame cover 86 is arranged on the upper surface of the frame 73.Referring to FIG. 134, the width of the upper end of the frame 73 is alittle wider than the frame body 81, and the upper end part of the frame73 protrudes a little to the interior and the upper end part isequivalent to the frame cover 86. FIG. 143 exemplary shows the framecover 86. As is shown in FIG. 143, the frame cover 86 is a thin plate.The frame cover 86 is bent downwards in an L shape at an exterior endpart and is fixed by a screw etc to the side surface of the frame body81 as shown in the diagram (the frame cover 86 may also be fixed toother places such as the upper surface of the frame body 81). Thematerial of the frame cover 86 may be a conductor, for example, copper.The exterior periphery shape of the frame cover 86 is almost the same asthe frame body 81. However, the aperture of the frame cover 86 issmaller than the aperture 85 of the frame body 81 and therefore, theframe cover 86 protrudes more to the interior than the frame body 81.When the substrate S is mounted, the interior periphery edge of theframe cover 86 overlaps the exterior periphery edge of the substrate Sand makes contact. The aperture size of the frame cover 86 is fixed sothat this overlapping is produced. Therefore, seen from above, the framecover 86 covers a gap between the frame 73 (frame body 81) and thesubstrate S. By arranging this frame cover 86 it is possible to preventbending of an equipotential surface on an edge part of the substrate S.The frame cover 86 is omitted from FIG. 137 and FIG. 138.

Two terminal parts 77 are arranged on the frame body 81. The terminalparts 77 protrude from the aperture 85. In addition, when the substrateS is mounted within the aperture 85, the terminal parts 77 contact theupper surface of the substrate S. As described above, the terminal parts77 are used to provide a potential to the upper surface of the substrateS during a substrate inspection. In addition, the frame cover 86described above covers a gap between the substrate S and frame 73 aroundthe entire frame except the terminal parts 77.

There are four frame legs parts 83 which are each arranged near thecorners of the frame boy 81. As is shown in FIG. 137, when lowered, theframe leg parts 83 are supported by the tray body 71 and the frame body81 is located above the tray body 71. In addition, the upper surface ofthe frame is located at almost the same height as the upper surface ofthe substrate S on the substrate mounting pins 75 (as is shown in FIG.143, specifically, the upper surface of the frame body 81 is located atthe same height as the upper surface of the substrate. The upper surfaceof the frame cover 86 is located at almost the same height as thesubstrate upper surface. However, specifically, the cover is a littlehigher than the substrate surface by the thickness of the cover. Thesame is true below). When the frame 73 is raised, an insertion opening79 is formed between the tray body 71 and the frame body 81 andinsertion and extraction of and access to the substrate S is madepossible.

In addition, as is shown in FIG. 134 and FIG. 135, a lift guide 87 isarranged in order to guide the lifting operation of the frame 73. Thelift guide 87 is a guide rod which protrudes from the tray body 71. Thelift guide 87 is inserted into a guide hole in the frame leg parts 83.In this way, the frame 73 can only be moved in a perpendicular directionwith respect to the tray surface.

In addition, as is shown in FIG. 133 etc, the tray body 71 includes aplurality of protruding edge parts 89. In the present embodiment, fourprotruding edge parts 89 are each arranged at each corner of the traybody 71. The protruding edge parts 89 are the parts which protrude moreto the exterior than the frame 73. Specifically, a wall part is arrangedat each corner of the tray body 71 and the protruding edge parts 89protrude to the exterior from the upper end of the wall parts. Theprotruding edge parts 89 are used for supporting the tray T by atransfer robot described below, and are used for supporting the traybody 71 when raising the frame 73.

(Stage)

A stage 53 is a structure for supporting a tray T. As is shown in FIG.129 and FIG. 130, the stage 53 includes a stage base 91. A plurality ofstage columns 93 are arranged on the stage base 91. In the presentembodiment, four stage columns 93 are arranged in locationscorresponding to the four corners of the tray T. In addition, the fourcorner of the tray body 71 are supported by the four stage columns 93.The tray T is movably supported in a horizontal direction and can bemoved when positioning by a clamp mechanism 57 described below.

As is shown in FIG. 129 etc, a substrate presence detection sensor 95,tray presence detection sensor 97, and substrate tilted placementdetection sensor 99 and tray diagonal placement detection sensor 101 arearranged on the stage 53. These sensors are attached to the stage base91.

(Lift Mechanism)

A lift mechanism 55 moves the frame 73 and substrate S in aperpendicular direction with respect to the tray planar surface, andlifts and lowers the frame 73 and substrate S.

As is shown in FIG. 130, FIG. 134, FIG. 137 etc, the lift mechanism 55includes a lift plate 111 which is plate shaped lift part. The liftplate 111 is driven by a lift cylinder 113 for the lift mechanism 55 andmoves vertically within a predetermined range in a downwards directionfrom the tray T.

A plurality of frame support pins 115 and a plurality of substratesupport pins 117 protrude upwards from the lift plate 111. The framesupport pins 115 and substrate support pins 117 are almost the sameheight.

The frame support pins 115 are equivalent to a frame support part of thepresent invention and are arranged at a location corresponding to thelower surface of the frame 73, and move vertically together with thelift plate 111. In the present embodiment, four frame support pins 115are arranged at a location corresponding to each of the four frame legparts 83 of the frame 73. As is shown in FIG. 135, when the liftmechanism 55 rises, the frame support pins 115 pass through a hole inthe tray body 71, contact with the lower surface of the frame leg parts83, lift up the frame 83 and the insertion opening 79 is formed betweenthe tray body 71 and the frame 73.

In addition, the substrate supports pins 117 are equivalent to asubstrate support part of the present invention and are arranged at alocation corresponding to the lower surface of the substrate S3 whenpositioning, and move vertically together with the lift plate 111. As isshown in FIG. 133, in the present embodiment, the four substrate supportpins 117 are arranged slightly misaligned from the four substratemounting pins 75 of the tray T. In addition, as is shown in FIG. 134 andFIG. 135, when the lift mechanism is raised, the substrate support pins117 pass through a hole in tray body 71 the same as the frame supportpins 115 and are raised. The tip end parts of the substrate support pins117 reach a position slightly above the tip end parts of the substratemounting pins 75 of the tray T. In this way, the substrate S issupported by the substrate support pins 117 before mounting on thesubstrate mounting pins 75.

Here, the location of the substrate S in a height direction whenmounting on the substrate mounting pins 75 of the tray T is called asubstrate mounting height. In addition, the location of the substrate Sin a height direction when being supported by the substrate supportingpins 117 of the lift mechanism 55 described above is called a substratesupport height. The substrate support height is above the substratemounting height as described above. Furthermore, the substrate supportheight is at a height corresponding to the insertion opening 79described above. The substrate supporting pins 117 reach the substratesupport height, the substrate S is supported at the substrate supportingheight by the substrate supporting pins 117 before being mounted to thesubstrate mounting pins 75, and the substrate S is clamped as describedbelow.

In addition, the substrate supporting pins 117 are formed from amaterial which is difficult to slide such as polychlorotrifluoroethylene(PCTFE, registered trademark). In this way, it is easy to position thesubstrate S.

In addition, as is shown in FIG. 130 etc, the lift mechanism includes aframe support height adjustment mechanism 119 for adjusting the heightof the frame supporting pins 115 and a substrate support heightadjustment mechanism 121 for adjusting the height of the substratesupporting pins 117. The frame support height adjustment mechanism 119includes a screw structure. An external thread is arranged on theexterior periphery of the frame supporting pins 115, and the externalthread joins with the internal thread of the lift plate 111 to enableadjustment of the pin height by rotating the frame support pins 115. Thesubstrate support height adjustment mechanism 121 includes the samescrew structure. With this structure the frame support height adjustmentmechanism 119 and the substrate support height adjustment mechanism 121can independently adjust the frame support pins 115 and the substratesupporting pins 117.

(Clamp Mechanism)

The clamp mechanism 57 is a structure for positioning the substrate Swith respect to the tray T. In the present embodiment the clampmechanism 57 moves in a direction parallel to the tray planar surfaceand clamps both the substrate S and tray T in one clamp operation. Theclamp mechanism 57 is described in more detail below.

As is shown in FIGS. 133, 136, 137 and FIG. 138 etc, the clamp mechanism57 is formed by a plurality of clamp bodies. In the example of thepresent embodiment, two clamp bodies, fixing side clamp body 131 anddriven side clamp body 133 are provided. The fixing side clamp body 131and driven side clamp body 133 are arranged facing each other alongdiagonal lines of the substrate S and tray T.

The fixing side clamp body 131 and driven side clamp body 133 are eachlinked respectively to a fixing side cylinder 135 and driven sidecylinder 137. The fixing side clamp body 131 is driven in a straightline by the fixing side cylinder 135 and the driven side clamp body 133is driven in a straight line by the driven side cylinder 137. In thisway, the clamp mechanism 75 is opened and closed. The fixing sidecylinder 135 and driven side cylinder 137 are equivalent to clampmovement mechanisms in the present invention.

The fixing side clamp body 131 includes two fixing side tray clamp arms139 and two substrate clamp arms 141. The tray clamp arms 139 andsubstrate clamp arms 141 extend towards the tray T. The height of thetray clamp arms 139 corresponds to the height of the tray body 71 andthe height of the substrate clamp arms 141 corresponds to the substratesupport height when supported by the substrate support pins 117 of thelift mechanism 55, and therefore, the substrate clamp arms 141 movevertically higher than the tray clamp arms 139.

The two ray clamp arms 139 are separated in a horizontal direction asshown in the diagram and each tray clamp arm 139 includes a tray clamppart 143 near a tip end part. The tray clamp part 143 is formed by asupport pin and contacts with the tray T when clamping for positioning.The movement direction of the clamp mechanism 57 is along the diagonalline of the tray T, therefore, diagonally with respect to a contactsurface. Thus, a pin of the tray clamp part 143 protrudes diagonallytowards a tray diagonal line from the tray clamp arm 139.

The substrate clamp arm 141 includes the same structure as the trayclamp arm 139, that is, the two substrate clamp arm 141 are separated ina horizontal direction and each substrate clamp arm 141 includes asubstrate clamp part 145 near a tip end part. The substrate clamp part145 is formed by a support pin and contacts with the tray T whenclamping for positioning. The movement direction of the clamp mechanism57 is along the diagonal line of the substrate S, therefore, diagonallywith respect to a contact surface. Thus, a pin of the substrate clamppart 145 protrudes diagonally towards a substrate diagonal line from thesubstrate clamp arm 141.

In addition, the exterior shape of the substrate S is smaller than thetray T. As a result, as is shown in FIG. 132, the substrate clamp arm141 protrudes considerably further than the tray clamp arm 139.

Next, the driven side clamp body 133 is explained. The driven side clampbody 133 has a narrower shape compared to the fixing side clamp body131.

The driven side clamp body 133 includes a tray clamp arm 147 andsubstrate clamp arm 149 which protrude towards the tray T the same asthe fixing side clamp body 131, the height of the tray clamp arm 147corresponds to the height of the tray body 71 and the height of thesubstrate clamp arm 149 corresponds to the height of the substrate Swhen supported by the substrate supporting pins 117 of the liftmechanism 55. There are two tray clamp arms 147 the same as the fixingside. However, unlike the fixing side there is only one substrate clamparm 149.

The two tray clamp arms 147 have the same structure as the fixing sideapart from having a narrower arm interval and shorter arm length. Thatis, the two tray clamp arms 147 are separated in a horizontal directionand each tray clamp arm 147 includes a tray clamp part 151 in near a tipend. The tray clamp part 151 has a support pin structure and contactsthe tray T when clamping. The pin of the tray clamp part 151 protrudesdiagonally towards the diagonal line of the tray.

There is one substrate clamp arm 149 as stated above. A substrate clamppart 153 is arranged at the arm end tip. The substrate clamp part 153 isa hollow part formed by cutting out the arm tip part. The substrateclamp part 153 contacts with two spots on end surface of the substrate Sat an edge part of both side of the hollow part when clamping.

In the present embodiment, the tray clamp arm 147 and the substrateclamp arm 149 are arranged so that the substrate clamp part 153 contactsthe substrate S before the driven side tray clamp part 151 contacts thetray T. In addition, as is shown in FIG. 132, the substrate clamp arm149 is arranged above a direct movement guide 155, and can move in astraight line along the clamp movement direction. In addition, a springpusher 157 is arranged to the rear of the substrate clamp arm 149. Thespring pusher 157 is equivalent to a bias part in the present invention.The substrate clamp arm 149 and substrate clamp part 153 are flexiblybiased towards the substrate S by the spring pusher 157. In addition,when the substrate clamp part 153 is pushed by the substrate S by therebound force of the clamp of the substrate S, the substrate clamp part153 continues to be flexibly biased towards the substrate S and can beretracted above the driven side clamp body 133. The function of theflexible structure described above is explained below.

In addition, a tray clamp location adjustment mechanism 159 andsubstrate clamp location adjustment mechanism 161 are arranged on thefixing side clamp body 131 in the clamp mechanism 57.

The tray clamp location adjustment mechanism 159 is arranged on eachtray clamp part 143 and has a structure for adjusting the amount ofprotrusion of the tray clamp 143 towards the tray T. The tray clamplocation adjustment mechanism 159 includes a screw structure. Anexternal thread is arranged on the exterior periphery of a support pinof the tray clamp part 143, and the external thread joins with theinternal thread of the tray clamp arm 139 to enable adjustment of thepin height by rotating the support pin. The substrate clamp locationadjustment mechanism 161 is arranged on each substrate clamp part 145and has a structure for adjusting the amount of protrusion of thesubstrate clamp 145 towards the substrate S. The tray clamp locationadjustment mechanism 159 and the substrate clamp location adjustmentmechanism 161 both include the same screw structure. With this structurethe amount of protrusion of the tray clamp body 143 and the substrateclamp part 145 of the fixing side clamp body 131 can independently beadjusted.

In addition, the driven side clamp body 133 also includes a tray clamplocation adjustment mechanism 163 the same as the fixing side clamp body131. The tray clamp location adjustment mechanism 163 is arranged oneach tray clamp part 151 and has the same screw structure as the fixingside.

In addition, in the examples of the present embodiment, the tray T isclamped at four locations, and the substrate is also clamped at fourlocations. However, the number of clamp locations is not limited tofour. The required minimum number of clamp locations is differentaccording to the shape of the tray and substrate. For example, in thecase where the substrate is round, the substrate may be clamped at 3locations.

(Tray Support Mechanism)

As is shown in FIGS. 130, 131, 134 and FIG. 137 etc, the tray supportmechanism 59 is a drive mechanism in a perpendicular direction withrespect to the tray planar surface. The tray support mechanism 59includes a plurality of tray support pins 171 which move down toward thetray body 71 and contact with the tray body 71. The tray support pins171 are equivalent to tray support parts in the present invention. As isshown in FIG. 131, the tray support pins 171 are attached to a pinattachment arm 173, links with a lift cylinder 175 for the tray supportmechanism 59 and the tray support pins 171 are moved vertically by thelift cylinder 175.

The tray support mechanism 59 has a function for preventing the traybody 71 from rising when raising the frame 73. That is, the tray supportmechanism 59 lowers the tray support pins 171 when the lift mechanism 55raises the frame 73 and the tray support pins 171 contacts with the traybody 71 thereby the tray body 71 is restrained and prevented from beingraised.

In the present embodiment, there are four tray support pins 171. Thefour tray support pins 171 are each arranged to correspond with theprotrusion edge part 89 of the four corners of the tray body 71, andcontact and press the protrusion edge parts 89 when lowering. In thisway, the upper surface of the protrusion edge parts 89 function ascontact parts of the tray support pins 171. Furthermore, the lowersurface of the protrusion edge parts 89 function as support surfaces forthe robot when transferring the tray.

In addition, as is shown in FIG. 131, the tray support mechanism 59includes a height adjustment mechanism 177 for adjusting the height ofthe tray support pins 171. The height adjustment mechanism 177 has thesame adjustment structure and screw structure as the lift mechanism 55.That is, an external thread is arranged on the exterior periphery of thetray support pins 171, and the external thread joins with the internalthread of the pin attachment arm 173 to enable adjustment of the pinheight by rotating the tray support pins 171.

(Frame Drop Mechanism)

As is shown in FIGS. 130, 131, 134 and FIG. 137, the frame dropmechanism 61 is a drive mechanism in a perpendicular direction withrespect to the tray planar surface. The frame drop mechanism 61 includesa plurality of frame drop pins 181 which move down toward the frame 73and press the frame 73. The frame drop pins 181 are equivalent to framedrop parts in the present invention. As is shown in FIG. 131, the framedrop pins 181 are attached to a pin attachment arm 183, links with alift cylinder 185 for the frame drop mechanism 61 and the frame droppins 181 are moved vertically by the lift cylinder 185.

In the present embodiment, there are four frame drop pins 181 and eachare arranged above the frame 73. The frame drop mechanism 61 lowers theframe drop pins 181 when releasing the frame lift after positioning iscompete by the clamp mechanism 57, presses the frame 73 and the frame 73is made to lands securely on the tray body 71. The landing of the frame73 may be detected and in this way a certain lowering operation can beguaranteed.

In addition, as shown in FIG. 131, the frame drop mechanism 61 includesa height adjustment mechanism 187 for adjusting the height of the framedrop 181. The height adjustment mechanism 187 has the same adjustmentstructure and screw structure as the lift mechanism 55. That is, anexternal thread is arranged on the exterior periphery of the frame droppins 181, and the external thread joins with the internal thread of thepin attachment arm 183 to enable adjustment of the pin height byrotating the frame drop pins 181.

The structure of each part in the substrate mounting device 51 relatedto the present embodiment was explained above. Next, the operations ofthe substrate mounting device 51 are explained.

FIG. 139 and FIG. 140 exemplary show an outline of the substratemounting device 51. As is shown in FIG. 139, the tray T is alreadyarranged on the stage 53 before the substrate S is mounted. The frame 73is lowered and the tray body 71 is supported by the frame leg parts 83.

The lift mechanism 55 is lowered and the frame support pins 115 andsubstrate support pins 117 are located at a lower position. The clampmechanism 57 is open, the fixing side clamp part 131 and the driven sideclamp part 133 are retracted to a predetermined waiting position.Furthermore, the tray support mechanism 59 and the drop mechanism 61 areraised and the tray support pins 171 and the frame drop pins 181 arelocated above the tray T.

When a mounting operation begins, first, the tray support mechanism 59lowers the tray support pins 171. The tray support pins 171 contact withthe protrusion edge part 89 of the tray body 71 and the tray body 71 ispressed.

Then, the lift mechanism 55 raises the frame support pins 115 and thesubstrate support pins 117. The frame support pins 115 pass through thehole in the tray body 71, contact with the lower surface of the frameleg parts 83, and the frame 73 is raised. At this time, the frame 73 isguided by the direct movement lift guide 87 (FIG. 135) arranged on theframe leg parts 83 and is raised in a vertical direction.

In addition, the substrate support pins 117 also pass through the holeof the tray body 71 and are raised the same as the frame support pins115. The tip ends of the substrate support pins 117 reach a slightlyhigher position than the substrate mounting pins 75 of the tray T.

The frame support pins 115 raise the frame 73 and thereby the insertionopening 79 is formed between the tray body 71 and the frame body 81. Thesubstrate S is inserted from the insertion opening 79 by a robot whichis a substrate transfer part (substrate transfer means), and set on thesubstrate support pins 117 having a substrate support height. Thesubstrate S is inserted from the arrow D direction in FIG. 133. Becausethe substrate support pins 117 protrude further than the substratemounting pins 75 of the tray T, the substrate S is supported not by thesubstrate mounting pins 75 but by the substrate support pins 117. Therobot described above is the atmosphere transfer robot 9 in FIG. 127.For example, the transfer robot includes a fork shaped arm whichsupports the lower surface of the substrate S at the arm end part andthe substrate is inserted by extending the arm.

Here, in the present embodiment the height of the end tip of the framesupport pins 115 and the height of the end tip of the substrate supportpins 117 is almost the same. However, the lower surface of the frame legparts 83 is located lower than the lower surface of the substrate S. Theframe support pins 115 contact the lower surface of the frame leg parts83 quicker than when the substrate support pins 117 contact with thelower surface of the substrate S. In addition, the lift mechanism 55 canraise the frame 73 by height amount of the frame leg parts 83. As aresult, the frame body 81 reaches a higher position than the substratesupport height of the end tip of the substrate support pins 117 and itis possible to form a sufficiently large insertion opening 79.

Next, as is shown in FIG. 140, the clamp mechanism 57 positions thesubstrate S with respect to the tray T. In the present embodiment, theclamp mechanism 57 accurately positions the substrate S by clamping thetray T and substrate S in one operation.

FIG. 141 is a diagram which explained the operations of a clamp. As isshown in the diagram, before the clamp is initiated, the fixing sideclamp body 131 and the driven side clamp body 133 are separated from thetray T and substrate S. When the clamp is initiated (when positioningbegins), first, the fixing side clamp body 131 is driven by the fixingside cylinder 135 (FIG. 136), moved up to a predetermined fixing sideclamp location and stopped.

Next, the driven side clamp body 133 is driven by the driven sidecylinder 137, contacts with the end part of the tray T and the end partof the substrate S and the tray T and substrate S are pressed towardsthe fixing side clamp body 131. The driven side tray clamp part 151presses the tray body 71 towards the fixing side tray clamp part 143,and the driven side substrate clamp part 153 presses the substrate Stowards the fixing side substrate clamp part 145.

In this way, the tray body 71 and the substrate S are clamped by oneclamp operation. The tray body 71 and the substrate S are positioned ata location which contacts with the fixing side clamp body 131. In thisway, the relative location relationship between the substrate S and thetray T is determined, and therefore, the substrate S is positioned withrespect to the tray T.

When clamping is complete, the driven side clamp body 133 is retractedand the substrate S and tray T are separated, then, the fixing sideclamp body 131 is retracted and the substrate S and tray T are separatedand thereby the clamp is released.

According to the present embodiment, the tray T and substrate S aresimultaneously positioned using a single clamping operation. The fixingside clamp body 131 includes a structure whereby the tray clamp part 143and the substrate clamp part 145 are arranged as a single unit, andtheir locational relationship is fixed. The tray T and substrate S arepressed to this fixing side clamp body 131. As a result, the locationsof the tray T and substrate S and the location of the substrate S withrespect to the tray T are determined corresponding to the locationalrelationship between the tray clamp part 143 and the substrate clamppart 145. Therefore, a high positioning accuracy can be obtained.

In addition, in the present embodiment, the fixing side clamp body 131advances forward as described above followed by the driven side clampbody 133. By providing the clamp mechanism 57 with this type ofstructure it is possible to obtain the merit whereby the amount of traymovement can be reduced.

In addition, in the clamp operation, the fixing side cylinder 135 andthe driven side cylinder 137 are controlled so that the clamp force ofthe driven side clamp is less than the clamp force of the fixing sideclamp. The fixing side clamp force is the force when the fixing sidecylinder 135 fixes the fixing side clamp body 131, and the driven sideclamp force is the force when the driven side cylinder 137 moves thedriven side clamp body 133. By adopting such clamp force settings, it ispossible to prevent misalignment of the fixing side clamp body 131 andobtained high positioning accuracy.

In addition, in the present embodiment, as already explained, thesubstrate support pins 117 protrude above the substrate mounting pins 75of the tray T. Therefore, as is shown in FIG. 140, when positioning, thesubstrate S is supported not by the substrate mounting pins 75 but bythe substrate support pins 117. The substrate mounting pins 75 include adifficult to slide surface considering a later stage transfer, while thesubstrate support pins 117 include a surface on which it is easy toslide. Therefore, the substrate S is places in a state whereby it easyto move in a horizontal direction. In this way, it is possible toprevent damage to the substrate S when positioning. In addition, becausethe substrate S securely moved to an appropriate location it is possibleto improve positioning accuracy.

In addition, as stated previously, in the present embodiment, the drivenside clamp body 133 includes the substrate clamp arm 149 above a directmovement guide 155, and a spring type pusher 157 is arranged on the rearside of the substrate clamp arm 149. This structure functions asdescribed below when clamping.

Referring to FIG. 142, in the present embodiment, the tray clamp arm 147and the substrate clamp arm 149 are arranged so that the substrate clamppart 153 contacts the substrate S before the driven side tray clamp part151 contacts the tray T.

Therefore, when the driven side clamp body 133 moves, first thesubstrate clamp part 153 contacts and presses the substrate S. Theopposite side of the substrate S contacts the fixing side clamp body131, the spring type pusher 157 contracts due to the rebound force fromthe substrate S and the substrate clamp arm 149 is retracted on thedirect movement guide 155. At this point, the substrate S is clamped bythe spring force of the spring type pusher 157. Then, the tray clamppart 151 contacts and presses the tray T. In addition, the substrate Sand the tray T are both clamped and positioned.

Here, the case where the direct movement guide 155 and the spring typepusher 157 are not arranged is explained temporarily. In this case,either the tray clamp part 151 or the substrate clamp part 153 can notcontact the object due to a dimension error and as a result, positioningaccuracy decreases. In the present embodiment, using the above describedstructure, the tray clamp part 151 and the substrate clamp part 153securely contact the tray T and substrate S and positioning accuracy canbe improved.

In addition, in the present embodiment, a flexible structure is appliednot to the tray T but to the substrate S. The substrate S is lighterthan the tray T and furthermore, the substrate S is supported by thesubstrate support pins 117 of the lift mechanism 55 when positioning.Therefore, the substrate S can move easily and even in the case when thesubstrate is pressed via a spring etc, it is possible to move thesubstrate for positioning more securely. In this way, positioningaccuracy can be further improved.

Returning to FIG. 140, when positioning is complete, after a clamp isreleased, the lift mechanism 55 is lowered and the frame support pins115 and the substrate support pins 117 are lowered. The frame 73 islowered, the frame leg parts 83 are supported by the tray body 71 andthe frame 73 returns to its original location. In addition, thesubstrate S is lowered and supported by the substrate mounting pins 75.The upper surface of the substrate S and the upper surface of the frame73 become the same height (as described above, specifically, the uppersurface of the frame body 81 is located at the same height as thesubstrate upper surface, and the upper surface of the frame cover 86 islocated slightly higher than the substrate upper surface). The terminalpart 77 of the frame 73 contacts the upper surface of the substrate S.In addition, the frame cover 86 covers the gap between the frame 73 andthe substrate S across the entire periphery of the substrate S (exceptthe two terminal parts 77).

When the lift mechanism 55 is lowered, the frame drop mechanism 61lowers the frame drop pins 181. The frame drop pins 181 contact andpress the upper surface of the frame 73. In this way, the frame dropmechanism 61 supports the lowering of the frame 73. The frame 73receives the effects of the frame drop pins 181 in addition to its ownweight and can be lowered securely to its original location.

Next, the frame drop mechanism 61 raises the frame drop pins 181 and thetray support mechanism 59 raises the tray support pins 171. In this way,a series of mounting operations is complete. When the mounting operationis complete, a robot transfers the tray on which the substrate S ismounted. The robot includes an arm and the arm supports the lowersurface of the protrusion edge parts 89 of the tray body 71. The robotis the atmosphere transfer robot 9 in FIG. 127 as stated above andtransfers the tray T to the load lock chamber 17.

An operation for mounting while positioning a substrate S on a tray Twas explained above. Next, an operation for removing a substrate S froma tray T is explained.

In the present embodiment, the substrate mounting device 51 is arrangedin an inspection device. When an inspection is complete, a tray T istransferred by a robot, and placed on a stage 53 of the substratemounting device 51. At this time, the substrate mounting device 51 is inthe same state as the when mounting is complete described above. Thatis, in the substrate mounting device 51, the lift mechanism 55 islowered and the frame support pins 115 and the substrate support pins117 are located in a lower position. The clamp mechanism 57 is open, andthe fixing side clamp body 131 and the driven side clamp body 133 areretracted to a predetermined waiting location. In addition, the traysupport mechanism 59 and the drop mechanism 61 are raised and the traysupport pins 171 and the frame drop pins 181 are located above the trayT.

First, the tray support mechanism 59 lowers the tray support pins 117and pushed against the tray body 71. Then, the lift mechanism 55 raisesthe frame support pins 115 and the substrate support pine 117. The frame73 is raised and the insertion opening 70 is formed between the traybody 71 and the frame body 81. The terminal part 77 of the frame 73 isseparated from the upper surface of the substrate S. The frame cover 86also moves to above the substrate S. In addition, the substrate S israised by the substrate support pins 117 of the lift mechanism 55. Inthis way, the substrate S is separated from the substrate mounting pins75 and floats above the tray.

Then, the robot extends its arm, the substrate S is accessed from theinsertion opening 79, the lower surface of the substrate S is supportedand the substrate S is removed from the insertion opening 79. Thesubstrate S is removed in the opposite direction to the arrow D in FIG.133.

Here, positioning may be performed again before the substrate removaloperation. Specifically, after the frame is raised, positioning isperformed by the clamp mechanism 57. The positioning operation may bethe same as the positioning operation in the substrate mounting process.Following this, the substrate is removed by the robot. In this way,positioning may be performed again and secure transfer can be improved.

When the substrate S is removed, the lift mechanism 55 is lowered, andthe frame 73 returns to its original location. At this time, the framedrop mechanism 61 lowers the frame drop pins 181 and supports thelowering of the frame 73. Then, the frame drop mechanism 61 raises theframe drop pins 181 and the tray support mechanism 59 raises the traysupport pins 171. In this way, a series of substrate removal operationis complete. Furthermore, the present embodiment can also be applied tothe embodiments 1˜28 and to embodiments that do not have numbersattached.

Other Embodiments

The substrate mounting device of the present invention was explainedabove. Examples of other embodiments of the present invention are asfollows.

A mask inspection device or method for inspecting a mask by irradiatinga charged particle beam onto a mask mounted on a tray using thesubstrate mounting device or method described above.

A mask manufacturing device or method for inspecting a maskmanufacturing process by irradiating a charged particle beam onto a maskmounted on a tray using the substrate mounting device or methoddescribed above.

A mask inspected by the mask inspection device or method describedabove. A mask manufactured by the mask manufacturing device or methoddescribed above.

A semiconductor manufacturing device or method for manufacturing asemiconductor device using the mask described above.

A semiconductor device manufactured using the mask described above. Asemiconductor device manufactured by the semiconductor manufacturingdevice or method described above.

For example, a Cr mask, EUV mask or nano-imprint mask can be given as atype of a mask. A Cr mask is used for light exposure, and the EUV maskis used for EUV exposure, the nano-imprint mask is used for forming aresist pattern by a nano-imprint. With regards to each of these masks, amask formed with a pattern may be the object of an inspection. Inaddition, a mask formed with a film before a pattern is formed may alsobe the object of an inspection.

Next, a manufacturing method of a semiconductor device which can apply amask obtained by the above described embodiments is described. Themanufacturing method includes the following processes (1)˜(5).

(1) a wafer manufacturing process for manufacturing a wafer (or a waferpreparing process for preparing a wafer(2) a mask manufacturing process for manufacturing masks to be usedduring the exposure (or mask preparing process for preparing masks)(3) a wafer processing process for performing any processing treatmentnecessary for the wafer(4) a chip assembling process for cutting out those chips formed on thewafer one by one to make them operable(5) a chip inspection process for inspecting finished chips

Among these main processes, the wafer processing process set forth in(3) exerts a critical effect on the performance of resultantsemiconductor devices. This process involves sequentially laminatingdesigned circuit patterns on the wafer to form a large number of chipswhich operate as memories, MPUs and so on. The wafer processing processincludes the following sub-processes:

(A) a thin film forming sub-process for forming dielectric thin filmsserving as insulating layers and/or metal thin films for forming wiringsor electrodes, and the like (by using CVD, sputtering and so on);(B) an oxidization sub-process for oxidizing the thin film layers andthe wafer substrate;(C) a lithography sub-process for forming a resist pattern by usingmasks (reticles) for selectively processing the thin film layers and/orthe wafer substrate;(D) an etching sub-process for processing the thin film layers and/orthe wafer substrate in accordance with the resist pattern (by using, forexample, dry etching techniques);(E) an ion/impurity injection/diffusion sub-process;(F) a resist striping sub-process; and(G) a sub-process for inspecting the processed wafer;

The wafer processing process is repeated a number of times depending onthe number of required layers. The lithography sub-process in (C)includes the following steps:

(a) a resist coating step for coating a resist on the wafer on whichcircuit patterns have been formed in the previous process(b) an exposing step for exposing the resist(c) a developing step for developing the exposed resist to produce aresist pattern(d) an annealing step for stabilizing the developed resist pattern

The preferred embodiments of the present invention are explained above.As described above, according to the present invention, the clampmechanism clamps both the tray and substrate in one clamp operation.This clamp operation is for pressing a tray and substrate from differentdirections using a plurality of clamps pieces. Because a clamp mechanismwhich moves parallel to a substrate planar surface is used, it ispossible to position the substrate without inclining the substrate. Inaddition, because the tray and substrate are clamped in one operationusing a clamp body arranged with a tray clamp part and substrate clamppart as one unit, the substrate is positioned with respect to the traycorresponding to a location relationship between the tray clamp part andsubstrate clamp part and the location relationship between the tray andsubstrate can be accurately determined. Therefore, the substrate can beaccurately positioned with respect to the tray.

In addition, according to the present invention, because the substrateand tray are clamped in one operation, it is possible to obtain themerit of being able to simultaneously position the tray as well as thesubstrate.

In addition, according to the present invention, because contact with asubstrate is made using a clamp it is possible to avoid contact with thesubstrate. It is preferred that the clamp is related after positioningis completed, and therefore, contact time can be reduced. Therefore,according to the present invention, it is possible to preferably performpositioning while avoiding as much contact as possible with thesubstrate.

In particular, in the examples of the embodiments described above, asubstrate is a mask and the substrate mounting device is arranged on acharged particle type inspection device (in particular, projection typeinspection device). In this case, both surfaces of the mask aresometimes inspected in sequence and it is necessary to avoid as muchcontact with both surfaces of the mask as possible. Therefore,performing highly accurate substrate mounting, mask positioning withoutcontact with a mask is being demanded. According to the presentinvention, it is possible to preferably meet the requests for such amask inspection.

In addition, the mask which is applied in the present invention is aglass manufactured mask having a square shape with 6 inch sides and athickness of 6.35 mm, which is heavy compared to a wafer. However, thistype of mask can also be preferably positioned with the substratemounting device of described above.

In addition, the inspection device applied with the present inventionperforms a mask inspection inside a vacuum chamber for example as isshown in the embodiments described above. However, the present inventioncan also preferably position a mask in this case.

In addition, in the example of the embodiments described above, thesubstrate mounting device performs temporary positioning of a substratewhen viewed from the entire inspection device. Actual positioning isperformed at a later stage. That is, a mark on a substrate is detectedby a CCD camera in a load lock chamber, tray set location is controlledin a main chamber based on the mark location, and actual positioning isperformed. The accuracy of this actual positioning is affected by theaccuracy of the temporary positioning. For example, when the field ofview of the CCD camera is broadened due to a low temporary positioningaccuracy, the magnification of the CCD camera decreases and accuracy ofthe actual positioning decreases. According to the present invention, itis possible to prevent a decrease in the accuracy of the actualpositioning and therefore improve inspection accuracy.

Other merits of the present invention are explained below. According tothe present invention, a fixing side clamp body and a driven side clampbody are arranged as a plurality of clamp bodies. First, the fixing sideclamp body may be arranged at a predetermined fixing side clamplocation, then, the driven side clamp body moves and the tray andsubstrate may be pressed towards the fixing side clamp body. Thelocation relationship between a tray clamp part and substrate clamp partof the fixing side clamp body may be fixed at the time of clamping. Inthis way, the fixing side clamp body and driven side clamp body becomelinked, and it is possible to accurately position the substrate to apredetermined location defined by the location relationship between thetray clamp part and substrate clamp part of the fixing side clamp body.In addition, because the driven side clamp body advances after thefixing side clamp body has advance, it is possible to obtain the meritwhereby it is possible to reduce the amount of tray movement in apositioning process.

In addition, in the driven side clamp body, the tray clamp part andsubstrate clamp part may be arranged so that the substrate clamp partcontacts the substrate before the tray clamp part contacts the tray, anda bias part may be arranged which flexibly biases the substrate clamppart towards the substrate when clamping. The bias part may be able toretract the substrate clamp part when the driven side substrate clamppart is pressed from the substrate due to the rebound force of thesubstrate clamp. The bias part may be a flexible part and may bearranged on the rear of the driven side substrate clamp part. Theflexible part may be a spring for example. By adopting this structure,it is possible to avoid a decrease in positioning accuracy due adimension error of the tray clamp part and substrate clamp part, and asubstrate can be positioned with a high level of accuracy. In addition,it is possible to further improve positioning accuracy by applying aflexible structure to the substrate which is lighter than the tray andcan move easily.

In addition, according to the present invention, the clamp body mayinclude a tray clamp location adjustment mechanism for adjusting theamount of protrusion by the tray clamp towards the tray and a substrateclamp location adjustment mechanism for adjusting the amount ofprotrusion by the substrate clamp towards the substrate. The amount ofprotrusion of the tray clamp part and the amount of protrusion of thesubstrate clamp part may be independently adjusted. By adopting thistype of structure, it is possible to adjust the amount of protrusion ofa tray clamp part and substrate part of the clamp body and furtherimprove positioning accuracy.

In addition, according to the present invention, the substrate mountingdevice may be arranged at a location corresponding to the substrate atthe time of positioning and may include a plurality of substrate supportparts which can be moved vertically. The clamp mechanism may clamp thesubstrate while the substrate is in a state supported at a substratesupport height which is higher than a substrate mounting height of atray by the plurality of substrate support parts. In this way, becausethe substrate is clamped while in a state separated from the tray, it ispossible to avoid friction between the tray and substrate whenpositioning. Therefore, it is possible to perform positioning with aslittle contact with the substrate as possible, prevent a decrease inpositioning accuracy due to friction and further prevent substratedamage due to friction.

In addition, according to the present invention, the tray may include atray body and a frame which can be raised from the tray body andencloses the substrate. The substrate mounting mechanism may be arrangedat a location corresponding to the frame and include a plurality offrame support parts which can be moved vertically. It is possible toform an insertion opening between the frame and tray body for insertingthe substrate and clamp body when the frame support part raises theframe. In this way, it is possible to provide a potential to thesubstrate upper surface from the frame on the substrate periphery. Inaddition, by enclosing the substrate with a frame, it is possible tomake a potential near the substrate end parts uniform. It is preferableof the frame contacts the substrate end part and thus it is possible topreferably make a potential uniform. In the embodiments described above,a frame cover is arranged so as to cover a gap between the frame andsubstrate, and the frame cover contacts the substrate end parts.Furthermore, in the present invention, because the frame is raised, itis possible to prevent interference between the clamp mechanism andframe, and preferably perform positioning using the clamp even when aframe is arranged in order to provide a potential to the substrate uppersurface.

More specifically, at lift mechanism may be arranged as explained in theembodiments described above. The lift mechanism may include a pluralityof frame support parts arranged at a location corresponding to a frame,and a plurality of substrate support parts arranged at a locationcorresponding to the substrate, and the plurality of frame support partsand plurality of substrate support parts may be linked and movedvertically. In addition, an insertion opening may be formed between theframe and tray body for inserting a substrate and clamp body when thelift mechanism raises the frame support parts and raises the frame.Furthermore, the lift mechanism raises the substrate support parts andmay protrude the substrate support parts to a substrate support heightwhich a height corresponding to the insertion opening which is higherthan the substrate mounting height of the tray. The substrate can beinserted by passing through the insertion opening and is supported bythe substrate supporting parts at a substrate support height. The clampbody can also be inserted through the insertion opening withoutinterference.

By adopting such a structure, it is possible to suitably raise a framein order to form an insertion opening. In addition, it is also possibleto support the substrate at a location above and separated from the traywhen positioning. Therefore, it is possible to preferably obtain themerits of the present invention described above. Furthermore, byarranging the frame support parts and substrate supports parts on acommon lift mechanism, it is possible to form a simple structure.

In addition, according to the present invention, the frame may alsoinclude a frame body which encloses a substrate and frame leg partswhich extend downwards from the frame body. The lower surface of theframe leg parts may be located lower than the lower surface of thesubstrate. The frame support parts may be arranged at a locationcorresponding to the frame leg parts and by supporting the frame legparts, the frame body may be located higher than the substrate supportheight by the substrate support parts and an insertion opening may beformed. With this structure, it is possible to raise the frame body to alocation higher than a substrate support height even when the substratesupport parts and frame support parts are simultaneously raised by thesame distance, and it is possible to preferably form an insertionopening for the substrate and clamp between the frame body and traybody. Therefore, the structure of the lift mechanism can be made simple.

In addition, according to the present invention, a substrate mountingmechanism may include a frame support height adjustment mechanism foradjusting the height of a frame supporting part and a substrate supportheight adjustment mechanism for adjusting the height of a substratesupporting part. The height of the frame support parts and the height ofthe substrate support parts may be adjusted independently. With thisstructure, it is possible to adjust the height of the frame supportparts and the height of the substrate support parts, and preferablyadjust the location relationship between the frame and substrate.

In addition, according to the present invention, a tray supportmechanism may be arranged. The tray support mechanism may include a traysupport part arranged at a location corresponding to the tray body andmay move the tray support parts vertically. The tray support mechanismlowers the tray support parts to contact with the tray body when thelift mechanism raises the frame and thereby the tray body may beprevented from being raised. With this structure, it is possible toprevent the tray body rising with the frame, and it is possible topreferably perform simultaneously positioning of the tray and substrateusing the clamp.

In addition, according to the present invention, the tray body mayinclude a protrusion edge part which protrudes further to the exteriorthan the frame, and the upper surface of the protrusion edge part may bea contact surface of the tray support part and the lower surface of theprotrusion edge part may be a support surface of the transfer robotwhich transfers a tray. With this structure, it is possible to use theprotrusion edge part of the tray body for tray support when mounting thesubstrate and tray transfer when mounting is complete. It is possible torealize these two functions with a simple structure.

In addition, according to the present invention, a frame drop mechanismmay be arranged. The frame drop mechanism may include a frame drop partarranged at a location corresponding to the frame, and may move theframe drop part vertically. The frame drop mechanism may lower the framedrop part when releasing the frame lift to press the frame. With thisstructure, the frame which is raised in order to prevent interferencebetween the substrate and clamp may be securely returned to a locationwhich encloses the substrate.

In addition, in the present invention, the substrate may be mask formanufacturing semiconductors. In addition, the substrate may have asquare shape. Conventionally, a positioning mechanism of a round shapedsubstrate is generally used, however, this can not be applied to squareshaped mask positioning. According to the present invention, squareshaped mask positioning can be preferably performed. However, within thescope of the present invention, the substrate is not limited to a maskand may also be a wafer. In addition, the substrate shape may round aswell as square. FIG. 144 shows an example of a substrate mounting devicein the case of a round shaped substrate. The round shaped substrate maybe a wafer for example. As is shown in the diagram, the shape of thetray is changed to a round shape to match the shape of the substrate.Except for changing the shape of the substrate and tray, the substratemounting device 201 in FIG. 144 includes almost the same structure asthe embodiments described above. The substrate mounting device 201 inFIG. 144 may be arranged with each structure of the present inventiondescribed above, that is, stage, lift mechanism, clamp mechanism, traysupport mechanism and drop mechanism etc. A structure view from ahorizontal direction (including a cross sectional structure) may bealmost the same as the embodiments described above with respect to asquare substrate.

The preferred embodiments of the present invention are explained above.However, the present invention is not limited to these embodiments. Aperson with ordinary skill in the field may make various modificationsof the embodiments described above within the scope of the presentinvention. Furthermore, the present embodiment can be applied toembodiments 1˜28 as well as embodiments with no number attached.

As stated above, the present invention is effective as a substratemounting technology which can position a substrate with respect to atray at a high level of accuracy.

Twenty Ninth Embodiment

Sample observation method and device, and an inspection method anddevice using the sample observation method and device.

An example of a sample observation method and device in the inspectiondevice and method of the present invention is explained.

[First Point of View]

The first point of view relates to observation of foreign materials, andin particular to a technique for inspecting foreign materials.

A purpose of the invention is to provide an electron beam inspectionmethod and an electron beam inspection device capable of quickly andreliably detecting a foreign material on a sample surface.

An electron beam inspection method according to the invention is forirradiating a sample surface with an imaging electron beam having apredetermined irradiation area, detecting reflected electrons by meansof a detector, and thereby acquiring an image of the sample surface andof a foreign material on the sample surface, and the electron beaminspection method has: a foreign material charging step of charging theforeign material by irradiation with a charging electron beam andforming around the foreign material a potential distribution differentfrom that of the sample surface; and a magnified image acquisition stepof detecting the electrons which are reflected from the foreign materialby the imaging electron beam irradiation and reach the detector througha path bent by the effect of the potential distribution, and acquiring amagnified image of the foreign material in which the magnification forthe foreign material is increased more than the magnification for thesample surface.

Since this allows an electron beam inspection to be carried out by usingthe electron beam having a predetermined irradiation area, a wide areacan be inspected quickly. Since the magnified image in which the foreignmaterial is magnified more than the surrounding sample surface isacquired, the foreign material can be detected reliably.

In the invention, the foreign material charging step may comprisenegatively charging up the foreign material by the charging electronbeam irradiation, and the magnified image acquisition step may comprisesetting the landing energy of the imaging electron beam to 10 eV orless, detecting mirror electrons reflected immediately in front of theforeign material, and acquiring the magnified image of the foreignmaterial.

This allows the magnified image of the foreign material to be reliablydetected by using mirror electrons which are easily generated in a lowlanding energy range.

In the invention, the foreign material charging step may compriseincreasing the absolute value of the potential of the foreign materialby the charging electron beam irradiation.

Consequently, the potential difference between the background samplesurface and the foreign material can be increased, the contrast of themagnified image of the foreign material can be increased, and theelectron beam inspection can be facilitated.

In the invention, the landing energy of the charging electron beam maybe larger than that of the imaging electron beam.

Consequently, the absolute value of the negative potential of theforeign material can be increased by the charging electron beamirradiation with a high landing energy. As a result, mirror electronscan easily be generated when the imaging electron beam irradiation isperformed.

In the invention, the landing energy of the charging electron beam maybe smaller than that of the imaging electron beam.

This configuration is suitable when an appropriate landing energy of theimaging electron beam is known. The above configuration can prevent apotential shift of the surface of the foreign material from increasingwhen the magnified image of the foreign material is acquired by usingthe imaging electron beam. Consequently, the magnified image can bedetected reliably.

In the invention, the charging electron beam and the imaging electronbeam may have the same landing energy and dose amounts different fromeach other.

This allows the charging of the foreign material to be controlled by thedose amount without changing the landing energy of the electron beam.Consequently, the magnified image of the foreign material can bedetected by easy control.

In the invention, the imaging electron beam may be made to enter thesample surface not perpendicularly thereto.

Consequently, the angle of incidence of the imaging electron beam can beadjusted appropriately, and the magnified image of the foreign materialcan be acquired at a higher resolution.

In the invention, the magnified image acquisition step may comprisesetting the landing energy of the imaging electron beam to 10 eV ormore, detecting secondary emission electrons reflected by being emittedfrom the foreign material, and acquiring the magnified image of theforeign material.

This allows secondary emission electrons to be generated from theforeign material to acquire the magnified image of the foreign materialbased on the secondary emission electrons, so that the electron beaminspection can be carried out.

In the invention, the landing energy of the imaging electron beam may beequal to or more than a maximum landing energy which causes allelectrons reflected from the sample surface to be mirror electrons andbe equal to or less than a value of a minimum landing energy, whichcauses all electrons reflected from the sample surface to be secondaryemission electrons, added with 5 eV.

In other words, in the invention, the landing energy LE of the imagingelectron beam may be set as LEA≦LE≦(LEB+5 eV), where LEA is the maximumlanding energy which causes all electrons reflected from the samplesurface to be mirror electrons, and LEB is the minimum landing energywhich causes all electrons reflected from the sample surface to besecondary emission electrons.

This allows the electron beam inspection to be carried out by using alanding energy range in which the difference in gray level is largebetween the foreign material and the surrounding sample surface.Consequently, the electron beam inspection can be carried out easily andreliably with the acquisition of a high-contrast image. Here the graylevel means the brightness of an image, and the difference in gray levelmeans the difference in brightness.

In the invention, the landing energy of the imaging electron beam may beset to a landing energy which: is in a landing energy range in whichelectrons reflected from the sample surface are a mixture of mirrorelectrons and secondary emission electrons, or only secondary emissionelectrons; is in a landing energy range in which electrons reflectedfrom the foreign material are a mixture of mirror electrons andsecondary emission electrons; and maximizes the difference in gray levelbetween the image of the sample surface and the magnified image of theforeign material.

This maximizes the difference in gray level between the surroundingbackground and the foreign material. Consequently, the foreign materialcan be detected in a state where the foreign material is easilydetected.

An electron beam inspection device according to the invention comprises:a stage for placing a sample thereon; a primary optical system forgenerating an electron beam having a predetermined irradiation area andfor emitting the electron beam toward the sample; and a secondaryoptical system, having a detector for detecting electrons reflected fromthe sample, for acquiring an image of a predetermined visual field areaon the sample, where the primary optical system charges the foreignmaterial by irradiation with a charging electron beam to cause thepotential distribution of the foreign material to be different from thatof a sample surface, and then irradiates the sample with an imagingelectron beam, and where the secondary optical system detects electronswhich are reflected from the foreign material and reach the detectorthrough a path bent by the effect of the potential distribution, andacquires a magnified image of the foreign material in which themagnification for the foreign material is increased more than themagnification for the sample surface.

This allows the whole sample surface to be inspected quickly by theelectron beam having an irradiation area of a predetermined size. Theforeign material can be detected reliably by magnifying the image of theforeign material larger than that of the surroundings.

In the invention, the primary optical system may charge up the foreignmaterial by irradiation with the charging electron beam and thenirradiate the sample with the imaging electron beam with a landingenergy of 10 eV or less, and the secondary optical system may detectmirror electrons reflected immediately in front of the foreign materialby means of the detector and acquire the magnified image of the foreignmaterial.

With the use of a low landing energy, this allows the foreign materialto be in a state where it easily generates mirror electrons. The use ofmirror electrons makes it easy to acquire the magnified image of theforeign material. Consequently, the foreign material can be detectedmore reliably.

In the invention, at least one of a Faraday cup, a reference samplechip, and an EB-CCD may be placed on the stage.

This allows the profile of the electron beam to be detected directly, sothat the electron beam can be adjusted appropriately.

In the invention, a reference sample chip may be placed on the stage,and the reference sample chip may have a circular, crisscross, orrectangular shape pattern.

This allows the beam profile of the electron beam to be adjusted so thatmirror electrons are suitably generated. Mirror electrons are suited todetect the magnified image of the foreign material, and the aboveconfiguration can generate mirror electrons appropriately.

In the invention, the primary optical system may set the landing energyof the imaging electron beam to 10 eV or more, and the secondary opticalsystem may detect secondary emission electrons which are emitted fromthe foreign material and reach the detector and acquire the magnifiedimage of the foreign material.

This allows the foreign material to be detected also by causingsecondary emission electrons to be generated from the foreign material.

In the invention, the secondary optical system may have an EB-CCDinterchangeable with an NA aperture.

This allows the profile of a secondary electron beam going through thesecondary optical system to be directly measured. Consequently, anappropriate adjustment can be made.

In the invention, the secondary optical system may have an NA aperture,which may be placed so that the center of the intensity distribution ofthe mirror electrons coincides with the center position of the aperture.

This allows the NA aperture to be appropriately positioned to detect themirror electron signal satisfactorily and to cause the detection amountof secondary emission electrons to be relatively small. Consequently, ahigh-contrast image can be acquired.

In the invention, the secondary optical system may have an NA aperture,and the shape of the NA aperture may be an elliptical shape having themajor axis in a direction corresponding to the longitudinal direction ofthe intensity distribution of the mirror electrons.

Consequently, the aperture of an elliptical shape adapted to theintensity distribution of the mirror electrons can be used. As a result,more mirror electron signals can be detected and a high-contrast imagecan be acquired.

In the invention, the secondary optical system may have an NA aperturehaving a plurality of apertures, and the NA aperture may be placed sothat the plurality of apertures are located around the center of theintensity distribution of the mirror electrons.

Here the NA aperture is an aperture member, and the plurality ofapertures are a plurality of openings provided on the aperture member.In the above-described configuration, the aperture can be placedaccording to the scattering direction of the mirror electrons, and themirror electrons can be appropriately detected depending on the intendeduse and property.

In the invention, the secondary optical system may comprise an NAaperture having a plurality of apertures, and the NA aperture may beplaced so that any one of the plurality of apertures coincides with thecenter of the intensity distribution of the mirror electrons.

Here the NA aperture is an aperture member, and the plurality ofapertures are a plurality of openings provided on the aperture member.In the above-described configuration, an effective inspection can becarried out for a foreign material distinctive in the scatteringdirection. An inspection useful in classifying foreign materials canalso be carried out.

In the invention, the secondary optical system may further comprise amoving mechanism for moving the NA aperture.

This allows the NA aperture to be positioned easily by using the movingmechanism.

In the invention, the primary and secondary optical systems may beoptical systems whose sensitivity is calibrated by using microspheres ofa known size scattered on the sample.

This allows the sensitivity calibration to be carried out precisely.Consequently, image acquisition can be carried out under goodconditions.

The electron beam inspection device of the invention may have: a chamberfor containing the stage; and an SEM-type inspection device provided inthe chamber, where based on positional information on the magnifiedimage of the foreign material acquired by the detector the stage may bemoved and the foreign material may be inspected in detail by theSEM-type inspection device.

Consequently, review inspection for the foreign material can be carriedout quickly and precisely, and the foreign material inspection can becarried out quickly and precisely.

EFFECTS OF THE INVENTION

As described above, the invention allows the foreign material inspectionto be carried out quickly and allows the foreign material to be detectedreliably and easily.

Embodiment of the Invention

Now, the invention will be described in detail. The following detaileddescription and appended drawings are not intended to limit theinvention. Rather, the scope of the invention is defined by the appendedclaims.

FIG. 145A shows an image to be obtained by an electron beam inspectionmethod according to an embodiment. An outline of the principles of theinvention will be described with reference to FIG. 145.

FIG. 145A shows an image 80 of a foreign material 10 obtained by aprojection method according to the embodiment. The size of the foreignmaterial is 40 nm. In the image in FIG. 145A, the size of the foreignmaterial 10 mostly covers an area of a pixel size of 2×2 [μm]. Here thepixel size is an actual size on a sample corresponding to one pixel of adetector. The pixel size means a minimum unit of the size of a samplethat can be observed. Hence in FIG. 145A the displayed image 80 ismagnified to almost as large as 2×2 [μm] despite the actual size of theforeign material being 40 nm. This means that the foreign material 10 ofabout 40 nm can be found even if the pixel size is about 1 μm or 1.5 μmlarge for example.

In FIG. 145A, the landing energy of an imaging electron beam is 1 [eV].The pixel size is 100 nm. Conventionally, the pixel size is required tobe less than 40 nm when the actual size of a foreign material is 40 nm.In contrast to this, the embodiment can acquire the magnified image ofthe foreign material 10 that is magnified more than the opticalmagnification.

FIG. 145B shows an image 280 of the foreign material 10 to be obtainedby a conventional foreign material inspection device of an SEM (scanningelectron microscope) type. The size of the foreign material is 40 nm. InFIG. 145B, the pixel size is 2×2 [μm] as in FIG. 145A. It can be seen,however, that the size of the image of the foreign material 10 isconsiderably small in FIG. 145B compared to that in FIG. 145A.

As seen above, the electron beam inspection method according to theembodiment can acquire an image in which the size of the foreignmaterial 10 is significantly increased, compared to the conventional SEMmethod. That is, a detection signal from the foreign material 10 ismagnified more than the optical magnification. High sensitivity can beachieved even for a foreign material of an ultra-micro size.Furthermore, a foreign material can be detected by using a pixel sizethat is larger than the actual foreign material.

FIG. 145C is a side view showing a state where the foreign material 10is present on a sample 20. In FIG. 145C, the surface of the foreignmaterial 10 is spherical. For this reason, electrons reflected from thesurface do not go through a vertical path, but change the path andspread out. This is for the following reason: since the foreign material10 has a spherical surface, the potential distribution of the foreignmaterial 10 is different from that of a sample surface 21; so, if thesample surface 21 is seen macroscopically, the potential distribution ofits part where the foreign material 10 is present is distorted; andtherefore the electron path changes. This will be described in detaillater.

FIG. 146A and FIG. 146B show conventional electron beam inspectionmethods for comparison. FIG. 2A shows a conventional optical-typeelectron beam inspection method. In the optical method, the foreignmaterial 10 is detected by a so-called dark-field scattering method.That is, the sample surface 21 of the sample 20 is irradiated with lightor a laser, and the scattered light is detected by a detector 170. Inthe conventional optical method, however, the detection sensitivitydecreases for ultra-micro foreign materials of a size between 50 and 100nm or less, organic deposits, or the like. It would therefore bedifficult to apply the conventional optical method. A major cause forthe sensitivity decrease is considered to be a decrease in S/N ratio dueto the foreign material 10 being smaller than the wavelength of light.

FIG. 146B shows a conventional SEM-type electron beam inspection method.In the SEM method, an ultra-micro pattern defect 22 or the like can bedetected by condensing the electron beam to reduce the pixel size. Forexample, a pixel size smaller than the size of an object foreignmaterial can be used, and therefore the foreign material 10 can beinspected for at a high resolution. However, since the pixel size issmall, the inspection requires an immense amount of time and isdifficult to carry out within a realistic time frame, so the SEM methodis not practical.

As seen above, there has been conventionally no foreign materialinspection method and foreign material inspection device that realizeshigh sensitivity, high speed, and high throughput in the inspection forforeign materials of an ultra-micro size between 50 and 100 nm or less.

FIG. 147A and FIG. 147B show an example of a magnified image 80 of theforeign material 10 to be acquired by the foreign material inspectionmethod and a cross-sectional gray level of the magnified image. Here thegray level means the brightness of an image, and the difference in graylevel is the difference in brightness. The higher the gray level is, thehigher the brightness is. FIG. 147A is an example of the magnified image80; more particularly, the white area in the center is a magnified image81 of the foreign material 10, and the black area shows a surface image82 of the sample 20. Here the size (diameter) of the foreign material is40 nm and the optical magnification is 300 times. In this case, the sizeof an image of the foreign material 10 would be 40 nm×the opticalmagnification 300=12 μm according to the conventional foreign materialinspection method. In the embodiment in FIG. 147A, the size of themagnified image 81 of the foreign material 10 is 190 μm. The pixel sizeof the detector is 15 μm.

FIG. 147B shows the cross-sectional gray level versus pixel position.The horizontal axis represents the pixel position coordinate, and thevertical axis represents the cross-sectional gray level. In FIG. 147Bthe triangular mark (A) indicates the mountain shape (protrusion shape)part. This part is an area in which the gray level is high, andcorresponds to the white magnified image part 81 in FIG. 147A. Thatmeans that the horizontal width (the triangular mark A) of the magnifiedimage 81 on the image 80 is 190 μm.

Here the pixel size of the detector 170 is 15 μm. The size of theforeign material would be displayed as 12 μm on the image 80 by theconventional method, and therefore an image of the foreign material 10would be a signal corresponding to one pixel or less. One pixel wouldnot be able to accurately represent the foreign material 10.

On the other hand, the magnified image 81 of the foreign material 10 canbe detected as an image whose number of pixels is 12.7 by the foreignmaterial inspection method according to the embodiment. The imaging cantherefore be carried out with a larger pixel size at a lowermagnification. If the imaging can be carried out with a large pixelsize, the whole sample surface 21 can be inspected quickly. Accordingly,the foreign material inspection can be carried out at high speed andhigh throughput. For example, the pixel size may be 100 to 1000 nm ifthe size of the foreign material is 10 to 30 nm. A pixel size largerthan the size of the foreign material can thus be used, and a quickforeign material inspection can be carried out.

An electron beam inspection device applied to the electron beaminspection method according to the embodiment has an electron beamcolumn (a primary optical system) of a projection type. In the SEMmethod, the electron beam is condensed. The spot size of the electronbeam is the pixel size corresponding to one pixel. In the projectionmethod, on the other hand, the electron beam has a predetermined areaincluding a plurality of pixels. The sample 20 is irradiated with suchan electron beam. A detector simultaneously detects electronscorresponding to the plurality of pixels. An image corresponding to theplurality of pixels is formed, and is acquired as an image signal. Asseen above, the projection optical system has: the electron irradiationsystem which irradiates the sample surface 21 with electrons; theoptical system for forming an image of electrons reflected from thesample surface 21 in a magnified manner; the detector 70; and the imageprocessing device system for processing the signal from the detector 70.

FIG. 148A shows a relation between the landing energy of the electronbeam with which the sample is irradiated and electrons emitted from thesample. More specifically, FIG. 148A shows the yield of secondaryemission electrons observed when the sample 20 is irradiated with theelectron beam with the landing energy being varied.

In FIG. 148A, the horizontal axis represents the landing energy LE(keV), and the vertical axis represents the ratio of the yield ofsecondary emission electrons to the amount of incident electrons.

In FIG. 148A, when the yield of secondary emission electrons is largerthan 1, the amount of emitted electrons is larger than the amount ofincident electrons. The sample therefore becomes positively charged. InFIG. 148A, the positive charge region is a region in which the landingenergy LE is 10 eV or more but not exceeding 1.5 keV.

In contrast, when the amount of secondary electron emissions is smallerthan 1, the amount of electrons incident on the sample 20 is larger thanthe amount of electrons emitted from the sample 20. The sample 20therefore becomes negatively charged. In FIG. 148A, the negative chargeregion is a region in which the landing energy LE is 10 eV or less and aregion in which the landing energy LE is 1.5 keV or more.

FIG. 148B shows mirror electrons. In FIG. 148B, the foreign material 10is present on the sample surface 21, and the foreign material 10 isnegatively charged. If the sample 20 is irradiated with an electron beamunder certain conditions, electrons in the electron beam do not collidewith the foreign material 10, but turn and are reflected immediately infront of it. Electrons that do not collide with an object to beirradiated but bounce back immediately in front of it like this arecalled mirror electrons. Whether electrons with which an object isirradiated become mirror electrons or not depends on the potentialdistribution (the state of charge) of the foreign material 10 and on thelanding energy of the electron beam with which the foreign material 10is irradiated. For example, if the foreign material 10 is negativelycharged up and the landing energy is not very high, the electron beam isbounced back by the negative electric field of the foreign material 10,is reflected without colliding with the foreign material 10, and becomesmirror electrons.

FIG. 148C shows secondary emission electrons. In FIG. 148C, the sample20 is irradiated with an electron beam, which collides with the samplesurface 21, and consequently secondary emission electrons are emittedfrom the sample. This is similar on the foreign material 10, where theelectron beam collides with the foreign material 10 and secondaryemission electrons are emitted from the foreign material 10.

In the electron beam inspection method according to the embodiment, theforeign material 10 present of the sample surface 21 is detected byusing mirror electrons and secondary emission electrons.

FIG. 149A and FIG. 149B show examples of a relation between the landingenergy LE of the electron beam with which the sample 20 and the foreignmaterial 10 are irradiated and “signal intensity/average gray level” ofelectrons reflected from the sample 20. Here “to be reflected” meansthat electrons oriented approximately opposite to the electron beamreturn from the sample 20 or foreign material 10 by the electron beamirradiation. Accordingly, “to be reflected” includes both of electronsthat are reflected without colliding with the sample 20 or foreignmaterial 10 and secondary emission electrons that are reflected bycolliding with the sample 20 or foreign material 10 and then beingemitted therefrom.

FIG. 149A is an example of a relation between the landing energy LE ofthe electron beam for the irradiation and “signal intensity/average graylevel” of reflected electrons. In FIG. 149A, the horizontal axisrepresents the landing energy LE of the electron beam, and the verticalaxis represents the “signal intensity/average gray level.” The averagegray level represents the brightness of an image and corresponds to thesignal intensity. FIG. 149 is the characteristic around the landingenergy LE being near 0 eV showing the characteristic in an energy rangewhich is far lower than that in FIG. 148. In FIG. 149A, the region inwhich the landing energy LE is 10 eV or less is a region in which amirror-electron-based signal (white) is acquired. On the other hand, theregion in which the landing energy LE is 10 eV or more is a region inwhich a secondary emission-electron-based signal (black) is acquired. Itcan be seen that, in the mirror electron region, the lower the landingenergy LE is, the more the signal intensity increases.

FIG. 149B shows an example different from that in FIG. 149A, and FIG.149B also shows a relation between the landing energy of the electronbeam for the irradiation and “signal intensity/average gray level” ofreflected electrons. In FIG. 149B, the region in which the landingenergy LE is 5 eV or less is a region in which a mirror-electron-basedsignal (white) is acquired, and the region in which the landing energyLE is 5 eV or more is a region in which a secondaryemission-electron-based signal (black) is acquired.

The characteristic line in FIG. 149B is different from that in FIG. 149Ain that the landing energy LE at the boundary between themirror-electron-based signal and the secondary emission-electron-basedsignal is 5 eV. The boundary of the landing energy LE between mirrorelectrons and secondary emission electrons varies depending on theproperties of the sample 20, the profile of the electron beam, and thelike, and can take on various values. The electron beam inspectionmethod and electron beam inspection device according to the embodimentwill hereinafter be described based on the example in FIG. 149A (theexample in which the landing energy LE at the boundary is 10 eV). Theinvention is not limited to this, however. As shown in FIG. 149B, theinvention may be applied when the landing energy at the boundary is 10eV or less and, for example, the landing energy at the boundary may be 5eV.

In FIG. 149A and FIG. 149B, the region in which the landing energy isthe boundary or less corresponds to the transition region of theinvention, where mirror electrons and secondary emission electrons aremixed. The region in which the landing energy is the boundary or morecorresponds to the secondary emission electron region of the invention.As described above, the boundary landing energy is 10 eV in the examplein FIG. 149A, and 5 eV in the example in FIG. 149A.

FIG. 150 shows a state where the foreign material 10 is present on thesample surface 21 of the sample 20. As illustrated, electrons aregenerated by irradiation with an electron beam. When the landing energyLE 10 eV; the foreign material 10 is negatively charged up. If anelectron beam enters the foreign material 10, an electron of theelectron beam becomes a mirror electron me. The electron is thereforereflected from the foreign material 10 without colliding therewith, andreaches the detector 70. Meanwhile, in the normal part where the foreignmaterial 10 is not present (the sample surface 21), a secondary emissionelectron se is generated by the irradiation with the primary electronbeam.

Here the “secondary emission electron se” means a secondary electron, areflected electron, or a backscattered electron. A mixture of them alsocorresponds to the “secondary emission electron se.”

The emission coefficient 11 of such secondary emission electrons isgenerally low. In particular when the landing energy LE is approximately50 eV or less, the emission coefficient 11<1.0. The closer the landingenergy LE comes to zero, the lower the emission coefficient becomes; andthe emission coefficient is almost zero when the landing energy LE=0.

There is also a distribution in the emission angle of electrons. Forexample, secondary electrons are distributed according to the cosinelaw. The transmittance of electrons that reach the detector 70 istherefore several percent or less in the projection optical system.

On the other hand, the mirror electron me is generated by an incidentelectron reflecting just before colliding with the foreign material 10.The mirror electron me is reflected from the foreign material 10 andenters a lens system of a secondary system at an angle approximatelysymmetrical to the angle of the incident primary electron beam. Thescattering and emission distribution are therefore small, and the mirrorelectron me reaches the detector 70 at a transmittance of approximately100 percent.

FIG. 151A shows the image 80 of the foreign material 10 on the samplesurface 21 to be acquired when the landing energy LE is 10 eV or less,and FIG. 151B shows the gray-level value of the image 80.

Referring to FIG. 151A, in the image of the sample surface 21 andforeign material 10, the magnified image 81 of the foreign material 10is shown as a white area, and the surface image 82 of the sample surface21 is shown as a black area. In this case, the brightness (the graylevel) is very high in a part where the mirror electron me is obtained.

FIG. 151B is an example of a relation between the y-directioncross-sectional position on the image 80 in the detector 70 and thegray-level value. The range in the y direction includes the magnifiedimage 81 of the foreign material 10. As shown in FIG. 151B, for example,the gray level of the mirror electron part is about three times as highas the part where the mirror electron me is not obtained. As a result,high brightness and a high S/N ratio can be achieved.

In the example in FIG. 151B, the part where the mirror electron me isobtained exhibits about three times as high gray-level value DN as thepart where the mirror electron me is not obtained. The relation of thegray-level value, however, varies depending on conditions or the like.The gray-level value of the mirror electron part may take on an abouttwo to ten times higher value.

FIG. 152 shows a state where the mirror electron me is generated fromthe foreign material 10 by the irradiation of the foreign material 10with the electron beam. The shape of the foreign material 10 causes ashift in the reflection point of the mirror electron me and thenonuniformity of the chargeup voltage. For this reason, the path andenergy of the mirror electron me are slightly shifted. Consequently,when the mirror electron me goes through a lens, beam filter, and thelike of the secondary system, the size of the signal area becomes large.

FIG. 152, the reflection direction of the mirror electron me radiallyspreads out from the effect of the surface potential of the foreignmaterial 10. Consequently, in a signal from the foreign material 10 thathas reached the detector 70, the signal size is magnified more than theoptical magnification of the electron optical system. The magnificationis, for example, 5 to 50 times.

For example, suppose that there is a secondary system with 100 timesoptical magnification. The signal size in the detector 70 for secondaryelectrons from the foreign material 10 is 100 times×0.1 μm=10 μm,according to a theoretical calculation.

On the other hand, the signal size of the mirror electron me from theforeign material 10 is magnified, for example, 30 times. Accordingly,the size of a signal entering the detector 70 is 300 μm. This phenomenonis equivalent to a magnification optical system that simply magnifies100 nm (0.1 μm) to 300 um. That is, a 3000 times magnification opticalsystem is achieved. This means that a pixel size larger than the foreignmaterial 10 can be used. If the foreign material 10 is 100 nm, the pixelsize may be larger than 100 nm. A pixel size of 300 to 1000 nm can beused.

By using a pixel size larger than an object foreign material, a largearea on the sample surface 21 of the sample 20 can be inspected at atime. This is therefore very effective in terms of quick inspection. Forexample, the inspection rate for a pixel size of 300 nm can be ninetimes faster than for a pixel size of 100 nm. The inspection rate can be25 times faster for a pixel size of 500 nm. That is, if one inspectionwould conventionally take 25 hours, the embodiment requires one hour forthe inspection. In contrast to this, imaging by the SEM method has to beperformed with a pixel size smaller than the size of the foreignmaterial, since the SEM method comprises forming a precise shape image,comparing it with an image of a normal part, and thereby detecting theforeign material.

As described above, the projection optical system not only can enhancethe difference in brightness between the mirror electron me and thesecondary emission electron se, but also can achieve speedups.

When the landing energy LE≦10 eV, precharge can be used suitably.Precharge is carried out by irradiating with a charging electron beambefore imaging.

Precharge may be carried out in order to increase the charge-up voltageof the foreign material 10. Precharge may also be carried out in orderto reduce the change in potential of the foreign material 10 duringimaging. In the foreign material inspection method, the amount of changein the charge-up voltage is controlled by a landing energy LE1 of acharging beam. For example, there are foreign materials 10 of varioussizes and various capacities. In this case, foreign materials 10 thatare charged to a certain charge-up voltage or less are detected by usingmirror electrons. The path of the mirror electrons is adapted by thedifference between the surrounding sample voltage and the charge-upvoltage, and consequently a state can be formed in which thetransmittance of the mirror electrons is I1igh. This will be describedin detail later.

Methods for precharge will next be described. There are three methodsfor precharge.

[Precharge-1]

FIG. 153A and FIG. 153B illustrate a first precharge mode (Precharge-1).Here the landing energy of the charging electron beam is LE1, and thelanding energy of the imaging electron beam is LE2. In Precharge-1, thelanding energy is set as LE2<LE1, which facilitates generation of mirrorelectrons.

In FIG. 153A, the foreign material 10 is present on the sample surface21, which is irradiated with the charging electron beam with the landingenergy LE1, and precharge is thus performed. The landing energy LE1 forthe precharge is larger than the landing energy LE2 of the imagingelectron beam. This increases the charge-up voltage of the foreignmaterial 10, causing electrons to become mirror electrons easily duringimaging. That is, by increasing the absolute value of the negativepotential of the foreign material 10, a reflection point in thepotential distribution created by the charge up is formed in front ofthe foreign material 10. Consequently, the incident imaging electronbeam is reflected, becoming the mirror electron me, before collidingwith the foreign material 10.

FIG. 153B shows a state where the foreign material 10 on the samplesurface 21 is irradiated with the imaging electron beam. In FIG. 153B,the foreign material 10 is negatively charged up and has anegative-voltage potential distribution. The imaging electron beam hasthe landing energy LE2 as described above. Under the effect of thesurface potential of the foreign material 10, an incident electron isreflected, becoming the mirror electron me, in front of the foreignmaterial 10 without colliding therewith. Meanwhile, the secondaryemission electron se is reflected from the sample surface 21 by beingemitted therefrom.

As seen above, in the configuration shown in FIG. 153A and FIG. 153B,the landing energy LE1 of the charging electron beam is set larger thanthe landing energy LE2 of the imaging electron beam. This allows themirror electron me to be suitably generated from the imaging electronbeam with which the foreign material 10 is irradiated, so that themagnified image 81 of the foreign material 10 can be acquired.

[Precharge-2]

FIG. 154 illustrates a second precharge mode (Precharge-2). InPrecharge-2, the landing energy LE2 of the imaging electron beam is setlarger than the landing energy LE1 of the charging electron beam. In theforeign material inspection method, imaging can be carried out with anappropriate potential variation being made during the imaging.

In FIG. 154, the horizontal axis represents the landing energy ofelectron beams, and the vertical axis represents the surface potentialof the foreign material 10. The landing energy LE1 of the chargingelectron beam is smaller than the landing energy LE2 of the imagingelectron beam. The surface potential of the foreign material 10 variesbetween LE1 and LE2. The potential difference ΔV is small asillustrated.

Precharge-2 in FIG. 154 is suitable when the landing energy LE2 of theimaging electron beam appropriate to imaging is known in advance. Simplyimaging with the imaging electron beam with the appropriate landingenergy LE2 would cause variations in the surface potential of theforeign material 10 during imaging and might be incapable of obtainingthe accurate magnified image 81. Precharge-2 avoids such a situation. Inthe configuration of Precharge-2, the surface potential of the foreignmaterial 10 is controlled by the precharge to reach close to the optimumvalue. This allows the potential change ΔV in the surface potential ofthe foreign material 10 to be reduced during imaging.

[Precharge-3]

FIG. 155 illustrates a third precharge mode (Precharge-3). InPrecharge-3, the landing energy LE1 of the charging electron beam is setequal to the landing energy LE2 of the imaging electron beam. The doseamount is then made to differ between the charging electron beam and theimaging electron beam. In FIG. 155, the horizontal axis represents thedose amount, and the vertical axis represents the surface potential ofthe foreign material 10.

Precharge-3 is effective for stabilizing the chargeup voltage of theforeign material 10 to achieve stable imaging and sensitivity. In FIG.155, a change in the dose amount causes variation in the surfacepotential of the foreign material 10. The precharge is carried out so asto give a dose D1 close to the required dose amount. A dose D2 is thengiven to perform imaging. Such a configuration is effective, and canreduce the potential variation ΔV of the surface of the foreign materialduring the imaging with the dose D2. Stable image quality (shape, focus,and the like) can therefore be achieved.

In the three types of precharges in FIG. 153 to FIG. 155, the beamsource of the charging electron beam for precharge may be the same asthat of the imaging electron beam, and the conditions of the beam sourcemay be controlled so as to carry out the above-described precharges. Aprecharge unit for precharge may also be provided separately. This canimprove the throughput.

The precharge unit may use a cathode comprising, for example, LaB6, a Wfilament, a hollow cathode, a carbon nanotube, or the like. Theprecharge unit may also use a Wehnelt for extracting the electron beam,an extraction electrode, a lens for controlling the irradiation area,and the like. The beam size of the precharge unit may be equal to or alittle larger than the beam size for regular irradiation by the columnsystem. The landing energy of the electron beam is determined by thevoltage difference between the cathode and the sample. For example,suppose that a negative voltage −3000 V is applied to the sample 20.Suppose also that the landing energy of the electron beam is set to 10eV. In this case, a cathode voltage −3010 V is applied to the cathode togenerate the electron beam.

(Another Inspection Method (for LE>10 eV))

FIG. 156 shows an image 80 a acquired by the detector 70 when thelanding energy LE of the electron beam is larger than 10 eV. In FIG.156, a magnified image 81 a of the foreign material 10 is represented bya black signal, and a surface image 82 a of the sample 20 is representedby a white signal.

FIG. 157A to FIG. 157C show the secondary emission electron se beingemitted from the foreign material 10 by irradiation with the imagingelectron beam.

FIG. 157A shows a behavior of the secondary emission electron se in astate where the foreign material 10 is charged up and the potentialdifference between the foreign material 10 and the surrounding samplesurface 21 is large. In FIG. 157A, the foreign material 10 is negativelycharged up, and the path of the secondary emission electron se from theforeign material 10 is bent. For this reason, the transmittance (theratio of electrons that reach the detector 70) extremely decreases. As aresult, the brightness of the foreign material part in the observedimage decreases as compared to the surroundings. This means that theforeign material 10 is detected as a black signal.

FIG. 157B shows a behavior of the secondary emission electron se in astate where the potential difference between the foreign material 10 andthe surrounding sample surface 21 is small. In FIG. 157B, since thepotential difference between the foreign material 10 and thesurroundings is small, electrons are generated from the foreign material10 and from the sample surface 21 in almost the same manner. For thisreason, it is difficult to distinguish the foreign material 10 from thesurroundings. That is, it is difficult to detect the foreign material 10from an acquired image. It is desired to avoid such a situation. So,even when the secondary emission electron se is to be detected from theforeign material 10, it is suitable to charge up the foreign material 10by irradiation with the charging electron beam. Applying the imagingelectron beam after the charge up facilitates detection of the foreignmaterial 10 as described above.

FIG. 157C shows a behavior of the secondary emission electron se in thepositive charge region. In the positive charge region, the secondaryemission electron se follows a path through which it is drawn by theforeign material 10 for a moment and then rises. As illustrated, thepath of the secondary emission electron se is bent by the effect of thepotential distribution of the foreign material 10, and the number ofelectrons that reach the detector 70 decreases. This phenomenon is thesame as FIG. 156A. Consequently, the same phenomenon is observed and themagnified image 81 a of the foreign material 10 is obtained as an imageof a black signal also in the positive charge.

In a foreign material inspection method and foreign material inspectiondevice according to the embodiment, an electron beam projection methodis used in order to further enhance the throughput. The use of aprojection system allows the secondary emission electron se or mirrorelectron me from the sample surface 21 to be used to detect foreignmaterials such as wafers and masks at high speed and high throughput, sothat, for example, foreign material inspection after sample cleaning issuitably carried out. As described above, since a detection signal fromthe foreign material 10 is magnified more than the opticalmagnification, a signal of the foreign material 10 of an ultra-microsize can be obtained with a large pixel size, so that high speed andhigh throughput is achieved.

For example, the size of the foreign material signal can be magnified 5to 50 times the actual size. A pixel size which is three times or morethe size of a foreign material to be detected can be applied. This isparticularly effective for the foreign material 10 of a size of 50 to100 nm or less. The optical method has difficulty detecting the foreignmaterial 10 of such size. The SEM method is required to use a pixel sizesmaller than the foreign material size. The throughput thereforesignificantly decreases if a small foreign material is to be detected.In the electron beam inspection method according to the embodiment, theforeign material 10 on a wafer in process can be quickly detected byusing the projection method. The acquisition of the magnified images 81and 81 a allows the foreign material 80 to be detected reliably.

(The Electron Beam Inspection Device)

FIG. 43 shows the structure of the electron beam inspection deviceapplied to one embodiment of the present invention. A foreign materialinspection device applied to carry out the above-described foreignmaterial inspection methods will be described here. Accordingly, all theforeign material inspection methods described above can be applied tothe foreign material inspection device described below.

The electron beam inspection device is to inspect the sample 20. Thesample 20 is a silicon wafer, a glass mask, a semiconductor substrate, asemiconductor pattern substrate, a substrate having a metal film, or thelike. The electron beam inspection device according to the embodimentdetects the presence of the foreign material 10 on a surface of thesample 20 comprising such a substrate. The foreign material 10 is aninsulating material, a conductive material, a semiconductor material, acomposite thereof, or the like. The type of the foreign material isparticle, noncleaned residue (organic matter), reaction product on thesurface, or the like. The electron beam inspection device may be anSEM-type device or a projection-type device. In this example, theinvention is applied to a projection-type inspection device.

The projection-type electron beam inspection device comprises: a primaryoptical system 40 for generating an electron beam; the sample 20; astage 30 for placing the sample thereon; a secondary optical system 60for forming a magnified image of secondary emission electrons or mirrorelectrons from the sample; the detector 70 for detecting thoseelectrons; an image processing device 90 (an image processing system)for processing a signal from the detector 70; an optical microscope 110for positioning; and an SEM 120 for reviewing. In the invention, thedetector 70 may be included in the secondary optical system 60. Theimage processing device 90 may be included in the image processor of theinvention.

The primary optical system 40 is configured to generate an electron beamand emit it toward the sample 20. The primary optical system 40 has: anelectron gun 41; lenses 42 and 45; apertures 43 and 44; an ExB filter46; lenses 47, 49, and 50; and an aperture 48. The electron gun 41generates the electron beam. The lenses 42 and 45 and the apertures 43and 44 shape the electron beam and control the direction thereof. Theelectron beam is then affected by a Lorentz force caused by the magneticand electric fields in the ExB filter 46. The electron beam obliquelyenters the ExB filter 46, and is deflected vertically downward towardthe sample 20. The lenses 47, 49, and 50 control the direction of theelectron beam and appropriately reduce the speed thereof to adjust thelanding energy LE.

The primary optical system 40 irradiates the sample 20 with the electronbeam. As described before, the primary optical system 40 carries outboth the charging electron beam irradiation for precharge and theimaging electron beam irradiation. According to an experimental result,the difference between the landing energy LE1 for the precharge and thelanding energy LE2 of the imaging electron beam is preferably 5 to 20eV.

Suppose in this regard that the irradiation for the precharge is carriedout with the landing energy LE1 in the negative charge region when thereis a potential difference between the foreign material 10 and thesurroundings. The charge-up voltage varies depending on the value ofLE1, since the relative ratio between LE1 and LE2 varies (LE2 is thelanding energy of the imaging electron beam as described above). A largeLE1 increases the charge-up voltage, causing a reflection point to beformed at a position above the foreign material 10 (a position closer tothe detector 70). The path and transmittance of mirror electrons varydepending on the position of this reflection point. An optimum charge-upvoltage condition is therefore determined according to the reflectionpoint. A too low LE1 decreases the efficiency of the mirror electronformation. In the invention, it has been found that this differencebetween LE1 and LE2 is desirably 5 to 20 eV. The value of LE1 ispreferably 0 to 40 eV, and more preferably 5 to 20 eV.

The ExB filter 46 is especially important in the primary optical system40 which is a projection optical system. The angle of the primaryelectron beam can be determined by adjusting electric and magnetic fieldconditions of the ExB filter 46.

For example, conditions of the ExB filter 46 can be set so that theirradiation electron beam of the primary system and the electron beam ofthe secondary system make approximately a right angle with the sample20. It is effective for further increasing the sensitivity, for example,to tilt the incident angle of the electron beam of the primary systemupon the sample 20. An appropriate tilt angle is 0.05 to 10 degrees, andpreferably about 0.1 to 3 degrees.

In FIG. 159, the foreign material 10 present on the sample surface 21 isirradiated with the primary electron beam. The tilt angle of theelectron beam is θ. The angle θ may be, for example, within a range of±0.05 to 10 degrees, and preferably within a range of ±0.1 to 3 degrees.

As seen above, irradiating the foreign material 10 with an electron beamtilted at a certain angle θ can enhance the signal from the foreignmaterial 10. This can create a condition in which the path of mirrorelectrons does not deviate from the center of the optical axis of thesecondary system, and can therefore increase the transmittance of themirror electrons. The tilted electron beam is thus very advantageouslyused when the foreign material 10 is charged up and the mirror electronsare guided.

Returning to FIG. 158, the stage 30 is a means of placing the sample 20thereon, and can move in the x-y horizontal directions and in the θdirection. The stage 30 may also be movable in the z direction asrequired. On the surface of the stage 30 may be provided a sample fixingmechanism such as an electrostatic chuck.

On the stage 30 is present the sample 20, on which the foreign material10 is present. The primary optical system 40 irradiates the samplesurface 21 with an electron beam with a landing energy LE of −5 to −10eV. The foreign material 10 is charged up, and incident electrons fromthe primary optical system 40 are bounced back without coming intocontact with the foreign material 10. This allows the mirror electronsto be guided through the secondary optical system 60 to the detector 70.At the same time, secondary emission electrons are emitted in spreadingdirections from the sample surface 21. The transmittance of thesecondary emission electrons therefore takes on a low value, forexample, of about 0.5% to 4.0%. In contrast to this, since the mirrorelectrons are not scattered in directions, a high transmittance ofapproximately 100% can be achieved for the mirror electrons. The mirrorelectrons are formed by the foreign material 10. Only the signal fromthe foreign material 10 can therefore cause a high brightness (a statewhere the number of electrons is large). The difference in brightnessfrom and the brightness ratio to the surrounding secondary emissionelectrons increase, allowing a high contrast to be obtained.

As described above, an image of the mirror electrons is magnified at amagnification larger than the optical magnification. The magnificationreaches 5 to 50 times. Under typical conditions, the magnification isoften 20 to 30 times. In such a case, a foreign material can be detectedeven if the pixel size is three times or more larger than the size ofthe foreign material. High speed and high throughput can therefore beachieved.

For example, when the size of the foreign material 10 is 20 nm indiameter, the pixel size may be 60 nm, 100 nm, 500 nm, or the like. Likethis example, a foreign material can be imaged and inspected for byusing a pixel size three times or more larger than the foreign material.This is a characteristic significantly superior to the SEM method andthe like in achieving high throughput.

The secondary optical system 60 is a means of guiding electronsreflected from the sample 20 to the detector 70. The secondary opticalsystem 60 has: lenses 61 and 63; an NA aperture 62; an aligner 64; andthe detector 70. Electrons are reflected from the sample 20 and gothrough the objective lens 50, lens 49, aperture 48, lens 47, and ExBfilter 46 again. The electrons are then guided to the secondary opticalsystem 60. In the secondary optical system 60, the electrons go throughthe lens 61, NA aperture 62, and lens 63 to be collected. The electronsare aligned by the aligner 64, and are detected by the detector 70.

The NA aperture 62 has a function of defining the transmittance andaberration of the secondary system. The size and position of the NAaperture 62 are selected so as to widen the difference between thesignal (mirror electrons etc.) from the foreign material 10 and thesignal from the surroundings (the normal part). Alternatively, the sizeand position of the NA aperture 62 are selected so as to increase theratio of the signal from the foreign material 10 to the signal from thesurroundings. Consequently, the S/N ratio can be increased.

For example, suppose that the NA aperture 62 can be selected in a rangefrom φ50 to φ3000 μm. Suppose also that mirror electrons and secondaryemission electrons are mixed in detected electrons. In order to improvethe S/N ratio of a mirror electron image under such conditions, theselection of the aperture size is advantageous. In this case, the sizeof the NA aperture 62 is preferably selected so that the transmittanceof the secondary emission electrons can be reduced to maintain thetransmittance of the mirror electrons.

For example, when the incident angle of the primary electron beam is 3degrees, the angle of reflection of the mirror electrons is almost 3degrees. In this case, it is preferable to select a size of the NAaperture 62 large enough to be able to let the path of the mirrorelectrons through. An appropriate size is φ250 μm, for example. Thetransmittance of the secondary emission electrons decreases since theyare limited by the NA aperture ( 250 μm in diameter). Consequently, theS/N ratio of a mirror electron image can be improved. For example, ifthe aperture diameter is changed from φ2000 to φ250 μm, the backgroundgray level (noise level) can be reduced to ½ or less.

The foreign material 10 may be formed of a material of any type, and maybe, for example, a semiconductor, an insulating material, a metal, orthe like. FIG. 160A and FIG. 1608 show a foreign material 10 a made of ametallic material, present on the sample surface 21. FIG. 1608 is anenlarged view of the foreign material 10 a made of a metallic material.In FIG. 1608, the foreign material 10 a may be a metal, a semiconductor,or the like, or a mixture thereof. As illustrated, a natural oxide film11 or the like is formed on the surface of the foreign material, andtherefore the foreign material 10 is covered by an insulating material.Accordingly, even if the material of the foreign material 10 is a metal,the charge up occurs on the oxide film 11. This charge up is suitablyused in the invention.

Returning to FIG. 158, the detector 70 is a means of detecting theelectrons guided by the secondary optical system 60. The detector 70 hasa plurality of pixels on its surface. Various two-dimensional sensorscan be applied to the detector 70. For example, a CCD (charge coupleddevice) and a TDI (time delay integration)-CCD may be applied to thedetector 70. These are sensors for detecting a signal after convertingelectrons to light, and therefore require a means of photoelectricconversion or the like. Photoelectric conversion or a scintillator istherefore used to convert the electrons to light. Image information ofthe light is transmitted to the TDI that detects light. The electronsare thus detected.

An example where an EB-TDI is applied to the detector 70 will bedescribed here. An EB-TDI does not require a photoelectric conversionmechanism and a light transmission mechanism. Electrons directly enterthe sensor surface of an EB-TDI. Consequently, the resolution does notdeteriorate, so that a high MTF (modulation transfer function) and highcontrast can be obtained. Conventionally, detection of the foreignmaterial 10 of a small size would be unstable. In contrast to this, theuse of an EB-TDI can increase the S/N ratio of a weak signal of thesmall foreign material 10. A higher sensitivity can therefore beobtained. The S/N ratio improves up to 1.2 to 2 times.

An EB-CCD may also be provided in addition to the EB-TDI. The EB-TDI andthe EB-CCD may be interchangeable, and may be arbitrarily interchanged.It is also effective to use such a configuration. For example, a methodof use shown in FIG. 161 is applied.

FIG. 161 shows the detector 70 in which an EB-TDI 72 and an EB-CCD 71can be interchanged. The two sensors can be interchanged depending onthe intended use, and both sensors can be used.

In FIG. 161, the detector 70 comprises the EB-CCD 71 and the EB-TDI 72.The EB-CCD 71 and the EB-TDI 72 are electron sensors for receiving anelectron beam. The electron beam e is made to enter the detectionsurface directly. In this configuration, the EB-CCD 71 is used to adjustthe optical axis of the electron beam, and is also used to adjust andoptimize imaging conditions. On the other hand, when the EB-TDI 72 is tobe used, the EB-CCD 71 is moved by a moving mechanism M to a positionaway from the optical axis. A condition determined by using the EB-CCD71 is then used or referred to, to image using the EB-TDI 72. The imageis used to carry out evaluation or measurement. Furthermore, themovement mechanism M is formed to be able to move the EB-CCD 71 not onlyin an X direction but tri-axially (for example, X, Y, Z directions) andmay be formed so to be able to adjust the center of the EB-CDD withrespect to the optical axis of the electron optical system.

With the detector 70, an electron optical condition determined by usingthe EB-CCD 71 can be used or referred to, to detect foreign materials ona semiconductor wafer using the EB-TDI 72.

After the foreign material inspection using the EBTDI 72, the EB-CCD 71may be used to carry out review imaging and make a defect evaluation ofthe type and size of foreign materials or the like. The EB-CCD 71 canintegrate images. The integration can reduce noise. Consequently, reviewimaging of an area where a defect has been detected can be carried outwith a high S/N ratio. In addition, it is effective for pixels of theEB-CCD 71 to be smaller than those of the EB-TDI 72. This means that thenumber of pixels of the imaging device can be large relative to the sizeof a signal magnified by the projection optical system. As a result, animage with a higher resolution can be obtained. This image is used forinspection, and for classification and determination of the type ofdefect or the like.

The EB-TDI 72 has a configuration in which pixels are arrangedtwo-dimensionally, and has, for example, a rectangular shape. Thisallows the EB-TDI 72 to directly receive the electron beam e to form anelectron image. The pixel size is, for example, 12 to 16 μm. On theother hand, the pixel size of the EB-CCD 71 is, for example, 6 to 8 μm.

The EB-TDI 72 is formed into a package 75. The package 75 itselffunctions as a feed through. Pins 73 of the package are connected to acamera 74 on the atmosphere side.

The configuration shown in FIG. 161 can eliminate various faults. Faultsto be eliminated are: optical conversion loss caused by an FOP, ahermetic optical glass, an optical lens, and the like; aberration anddistortion during light transmission; and the resulting deterioration inimage resolution, detection errors, high cost, growth in size, and thelike.

FIG. 162A and FIG. 162B illustrate a method of efficiently determiningelectron beam path conditions, the method being effective when a mirrorelectron image is to be obtained. The electron beam path conditions are:lens conditions of the lenses 42, 45, 47, 49, 50, 61, and 63 of theprimary optical system 40 and secondary optical system 60; and analigner condition of the aligner 64.

FIG. 162A shows a configuration in which a layered structure of apolysilicon layer 23 and a silicon dioxide film 24 is provided on thesample surface 21 of the sample 20 of a silicon substrate. A hollowgroove 25 is formed in a cut in the layered structure. In FIG. 162B, asilicon dioxide layer 24 a is formed on the sample surface 21 of thesample 20 of a silicon substrate. A hollow groove 25 a is formed in acut in the layer.

FIG. 162A shows a signal intensity distribution diagram mes of themirror electron me. A landing energy set in an area where the mirrorelectron me is generated causes the path of incident electrons to bendeasily, causes the mirror electron me to be generated easily at edgeparts 26 of the pattern, and causes the signal intensity at the edgeparts 26 of the hollow groove 25 to increase.

FIG. 162B shows a path through which an electron beam EB enters and themirror electron me is reflected. Electrons enter the sample 20, arereflected from an edge part 26 a on one side to travel approximatelyhorizontally, move to the opposite side of the hollow groove 25 a, andare reflected from an edge part 26 a on the opposite side to rise. Inthis way, mirror electrons are easily generated at the edge parts of thehollow groove 25 a.

Such a phenomenon is particularly noticeable in a hollow symmetricalstructure. The symmetrical structure is, for example, a Faraday cup, across-shaped groove structure, or the like. Here the symmetry of mirrorelectrons generated at the edge parts 26 and 26 a has an effect on theresolution of the image. It is desired to achieve the symmetry of thegray level so that the difference in gray level between both edges inthe image is 15% or less. The gray level is the brightness of the image,and the difference in gray level is the difference in the brightness.Adjusting the lens conditions and the aligner condition so as to be ableto obtain such symmetry allows the lens and aligner conditions to beoptimized for mirror electrons. A mirror electron image with a highresolution can thus be achieved. The S/N ratio can be improved by 10 to30% and the adjustment time can be reduced by about 10 to 50%, ascompared to when this adjustment method is not used.

FIG. 163 is a cross-sectional side view showing a Faraday cup 31. TheFaraday cup 31 comprises an opening 32 in a conductor, and a cuppedmetal electrode 33. The Faraday cup 31 measures the amount of electronsthat have gone through the opening 32 by means of an ammeter 34. Theopening 32 may be, for example, about 30 μm in diameter. Since theFaraday cup 31 has a hollow groove shape, mirror electrons are easilygenerated at the edge parts as described above. The Faraday cup 31 cantherefore be used for adjustment.

An example where the foreign material inspection method according to theinvention is applied to the foreign material inspection device in FIG.158 will next be described.

The aforementioned FIG. 148A shows a correlation between the “secondaryelectron yield” and the “landing energy LE.” This correlation suggests amechanism for detecting the foreign material 10 using an electron beamwith LE>10 eV. The secondary electron emission coefficient variesdepending on the landing energy LE with which the foreign material 10 isirradiated. For this reason, a negative charge state and a positivecharge state are formed. For example, when the insulating material isSiO2, the following charge states can be seen:

50 eV≧LE: negative charge;50<LE≦1500 eV: positive charge; and1500 eV<LE: negative charge.

In each case, the foreign material 10 is charged up, causing the foreignmaterial and the surroundings to be different from each other in thevalue of the potential, so that the potential distribution around theforeign material is distorted. This distorted electric fieldsignificantly bends the path of secondary electrons emitted from theforeign material 10 and reduces the transmittance thereof. Accordingly,electrons that reach the detector from the foreign material areextremely small in number as compared to those from the surroundings ofthe foreign material. As a result, the brightness for the foreignmaterial becomes lower (black signal) than that for the surroundings,and the foreign material 10 can be detected with a high contrast. Theblack signal of the foreign material is magnified in size more than theoptical magnification. A signal of the foreign material magnified 5 to20 times can be captured. These phenomenon and detection can besimilarly achieved in the above-described three energy regions.

An example of a projection-type electron beam column using an electronbeam will next be given. The sample 20 may be a wafer, a mask forexposure, a recording medium, or the like. If it is a wafer, a circuitpattern in process of LSI manufacture may be formed on a silicon waferof 8 to 12 inches. The wafer may also have no pattern. The wafer may bein a state where it has no pattern after film formation. The wafer maybe in a state where it has been subjected to a planarization process,such as grinding and CMP, after film formation. The wafer may be an Sisubstrate or the like before film formation or other process.

This sample 20 is placed on the x-y-θ control stage 30. The electronbeam is emitted from the electron gun 41. The beam irradiation area andthe irradiation energy are controlled by the lens 42, the apertures 43and 44, the quadrupole lens 45, the ExB filter 46, and the like, and thesample surface is irradiated with the electron beam. For example, thebeam diameter is φ300 μm (or an ellipse of about 270 μm×80 μm). Theprojection optical system forms on the detector 70 an image of emissionelectrons emitted from the sample surface 21 at a magnification of 50 to500 times. A negative voltage is applied to the sample 20. The potentialof the principal plane of the first lens 50 of the primary opticalsystem 40 is positive. Accordingly, a positive electric field is formednear the sample 20. For example, the positive electric field may be 1 to3 kV/mm. The detector 70 comprises an MCP (micro channel plate), afluorescent plate, an FOP (fiber optical plate), and a TDI (the internalconfiguration is not illustrated). The MCP multiplies the amount ofelectrons to be detected, and the fluorescent plate converts theelectrons to an optical signal. This two-dimensional optical signal istransmitted by the FOP, and the TDI sensor forms the image and detectsthe signal. When the TDI is used, the two-dimensional image signal isacquired with the sample being continuously moved. Consequently, theimage signal acquisition can be carried out quickly. The imageprocessing mechanism processes the signal transmitted from the TDI tocarry out electron image formation, foreign material detection, andforeign material classification and distinction.

An example where the foreign material 10 on the sample 20 is inspectedfor by using such an electron beam column will be described. The landingenergy LE of the primary electron beam with which the sample 20 isirradiated is set to 2 eV. The landing energy LE is the differencebetween the cathode voltage of the electron gun 41 of the primaryoptical system 40 and the voltage (applied voltage) of the sample.Irradiation with this electron beam causes the foreign material 10 to becharged up. Then, only the beam with which the foreign material 10 isirradiated becomes mirror electrons. The mirror electrons are guided bythe secondary optical system 60 to the detector 70. From the normal partwhere the foreign material 10 is not present, secondary emissionelectrons caused by the beam irradiation are guided to the detector 70.The secondary emission electrons are secondary electrons, reflectedelectrons, or backscattered electrons. These electrons may be mixed.

Here the closer LE is to zero, the lower the emission coefficient 11 ofthe secondary emission electrons becomes. In addition, directions of theemission from the surface show a divergent distribution (for example,the distribution of secondary electrons follows the cosine law). Forthis reason, a design calculation of the secondary emission electronsthat reach the detector 70 in the secondary optical system 60 indicatesthat the arrival rate of the secondary emission electrons is aboutseveral percent. As seen above, the arrival rate of the mirror electronsis high, and the arrival rate and emission coefficient of the electronsfrom the surrounding part are low. Accordingly, there occurs arelatively large ratio between the numbers of electrons, that is, adifference in brightness. Consequently, a large contrast and S/N ratiocan be obtained. For example, if the pixel size is 100 nm and thediameter of the foreign material is φ20 nm, the S/N ratio is between 5and 10. Generally, S/N≧3 is sufficient to carry out the detection andinspection. The invention therefore allows inspection for the extremelysmall foreign material 10 like the above example to be achieved with apixel size larger than the size of the foreign material.

An example where the charging electron beam for precharge is used in theabove-described device system will be described.

LE1 is the landing energy of the charging electron beam for precharge,and LE2 is the landing energy of the electron beam for the imaging andinspection. The insulating foreign material 10 can be efficientlyinspected for under conditions LE1:14 eV and LE2:1 eV. The foreignmaterial 10 on the surface of Si, an SiO₂ film, a metal film, an SOI, aglass mask, or the like can be inspected for. In this process, the wholesurface of the inspection area is irradiated with the charging electronbeam with LE1=14 eV. Irradiation with the imaging electron beam is thenperformed with LE2=1 eV to carry out the imaging and inspection for theforeign material 10. The execution of this process depends on how longthe effect of the precharge can be maintained. Under normal conditions,the effect of the precharge can be maintained for about 10 to 30 hours,and for 150 hours or more in some cases, if no charge removal process orthe like is applied.

As compared to when no precharge is performed, performing such prechargecan enhance the effect of the mirror electron formation, and can improvethe S/N ratio about three to ten times.

If the landing energy is LE≦10 eV, and particularly if it is in a regionLE≦0 eV, mirror electrons can be formed in the normal part. Even if thiscondition is set, the invention can create the conditions in which themirror electrons from the foreign material 10 reach the detector 70 andthe mirror electrons from the normal part do not reach the detector 70,and can carry out the inspection for the foreign material 10 with a highS/N ratio. More specifically, the sample surface 21 is flat, and theelectron beam enters almost perpendicularly. The incident beam on thenormal part is slowed down on the sample surface 21. For this reason,the path of the electrons is bent, and deviates from the center of thesecondary optical system 60. As a result, this phenomenon reduces thenumber of electrons guided from the normal part to the detector 70. Onthe other hand, the mirror electrons from the foreign material 10 risefrom a curved surface or an inclined surface of the foreign material 10,and is guided through a path near the center of the secondary opticalsystem 60 to the detector 70. Consequently, the mirror electron signalfrom the foreign material 10 is guided to the detector with a hightransmittance. A high S/N ratio can thus be achieved. This will bedescribed in detail with reference to FIG. 164.

FIG. 164 illustrates filtering for when mirror electrons are emittedfrom the foreign material 10 and the surrounding normal part. In FIG.164, the sample 20 with the foreign material 10 being present thereon isirradiated with an electron beam, and mirror electrons are reflectedfrom both the foreign material 10 and the sample surface 21. In such acase, the invention causes a phenomenon in which the mirror electronsreflected from the foreign material 10 reach the detector 70 and themirror electrons from the sample surface 21 of the normal part do notreach the detector 70. That is, the foreign material 10 is charged up,causing a potential difference between the foreign material and thesurrounding normal part (the sample surface 21), and this allows forseparation of the mirror electrons from the foreign material 10 and themirror electrons from the sample surface 21 of the surrounding normalpart.

For example, as described with reference to FIG. 159, the angle ofincidence of the primary electron beam is slightly tilted to thevertical and is caused to deviate from the center. This can create acondition where the path of the mirror electrons goes near the center ofthe secondary optical system 60. The path of the mirror electronsdeviates on the flat normal part. The path of the mirror electrons fromthe normal part deviates from the central part of the secondary opticalsystem 60, thereby reducing the amount and probability of electronsreaching the detector 70. The mirror electrons from the normal part alsobecome stray electrons or the like due to their collision with thecolumn of the secondary optical system 60. Consequently, there occurs adifference in the amount or density of electrons that reach the detector70 between the foreign material 10 and the surrounding sample surface21. This allows a large gray-level difference, i.e. contrast, to becreated.

Here the factors that have an effect on the deviation of the path arethe intensity and focus of the lenses 47, 49, 50, 61, and 63, the ExBfilter 46, and the NA aperture 62. The focus and intensity of the lenses47, 49, 50, 61, and 63 are adjusted so as to obtain a condition in whichthe path of the mirror electrons from the foreign material 10 goesthrough the center of the secondary optical system 60. The angle ofincidence and focus of the lenses are different between the mirrorelectrons from the surrounding normal part (the sample surface 21) andthose from the foreign material 10. The mirror electrons from the normalpart therefore go through paths that are off the center of the secondaryoptical system 60. The NA aperture 62 blocks the mirror electrons goingthrough paths that are off the center, and reduces the amount andprobability of them reaching the detector 70. Additionally, the ExBfilter 46 is adjusted so that when the mirror electrons go through theExB filter 46, the mirror electrons from the foreign material 10 gothrough the path that reaches the subsequent NA aperture 62 and detector70. This allows the mirror electrons to be appropriately adjusted whenthey go through the ExB filter 46. The angle of incidence on the ExBfilter 46 and the energy in the axial direction (the z-axis direction)are different between the mirror electrons from the foreign material 10and those from the surrounding normal part (the sample surface 21).Accordingly, the mirror electrons reflected from the sample surface 21of the normal part deviate from the center of the subsequent NA aperture62 and lenses 61 and 63. As a result, their probability of incidence onthe detector 70 decreases.

Generally, the LE region that can be used effectively is between −30 and0 eV. However, when the optical axis of the secondary optical system 60is not perpendicular to the sample surface, mirror electrons aresometimes formed even if LE is 0 eV or more. Also in a sample withmicroscopic unevenness on the surface such as a wafer with a pattern,mirror electrons are sometimes formed even if LE is 0 eV or more. Forexample, such a condition may be created in an LE region from −30 to 10eV.

The electron beam inspection method according to the invention can alsobe applied to the SEM by using the precharge effectively. For example,the foreign material inspection can be carried out with the SEM byimaging and inspecting after the precharge under the followingcondition:

Precharge LE1: 0 to 30 eV; and Imaging LE2: −5 to 20 eV.

For example, imaging is performed under conditions Precharge LE1=25 eVand Imaging LE2=5 eV. In this case, the foreign material (an insulatingmaterial or an object including an insulating material) is charged up,and the surface potential becomes negatively charged (e.g. −7 V).Irradiation is then performed with the imaging electron beam (LE2=5 eV).Consequently, mirror electrons are formed only in the charged-up foreignmaterial part, and the mirror electrons are acquired by the detector 70.The normal part without the foreign material 10 generates secondaryemission electrons (the secondary emission electrons are secondaryelectrons, reflected electrons, or backscattered electrons, or these maybe mixed). Since the emission coefficient of the secondary emissionelectrons is low, the brightness of the normal part is low. Thebrightness difference (the contrast) between the mirror electrons fromthe foreign material 10 and the secondary emission electrons from thenormal part is large, and therefore the foreign material 10 can bedetected with high sensitivity.

A precharge device may be provided in front of the imaging unit for anefficient precharge.

If no precharge is performed in the SEM method, there may be thefollowing faults. Generally in the SEM method, the spot size of theelectron beam is set smaller than the size of the object such as apattern defect and foreign material to be detected in order toappropriately perform image formation and shape recognition of thepattern or foreign material 10. Consequently, the difference between thebeam spot size and the foreign material size causes a local and temporalchange in the charge-up potential of the foreign material 10. As aresult, no stable signal can be obtained, or it is difficult to obtainstable mirror electrons. It is thus important to perform imaging afterstabilizing the surface potential condition of the foreign material 10or stabilizing the chargeup condition and potential of the foreignmaterial 10 using the precharge.

In conventional SEM methods, since beam scanning is performed, the angleof incidence of the beam relative to the sample 20 considerably variesdepending on the scan position. When a beam of mirror electrons isformed, the angle of reflection of the beam varies depending on theangle of incidence. Consequently, the probability of the electronsentering the detector 70 considerably varies depending on the scanposition, and this is a fault. For this reason, it is difficult toacquire a uniform and precise image. In order to overcome this fault,the aligner and the lens voltage are suitably adjusted in conjunctionwith each other so that the angle of incidence of the electron beamrelative to the sample will be almost a right angle.

As seen above, the electron beam inspection method according to theinvention can also be applied to the SEM method by establishingappropriate conditions.

FIG. 165 shows an electron beam inspection device to which the inventionis applied. Here an example of a general system configuration will bedescribed.

In FIG. 165, the foreign material inspection device has a sample carrier190, a minienvironment 180, a load lock 162, a transfer chamber 161, amain chamber 160, an electron beam column system 100, and an imageprocessing device 90. The minienvironment 180 is provided with anatmospheric transfer robot, a sample alignment device, a clean airsupply mechanism, and the like. The transfer chamber 161 is providedwith a vacuum transfer robot. Since the robot is placed in the transferchamber 161 which is always in a vacuum state, the generation ofparticles or the like caused by pressure fluctuations can be suppressedto a minimum.

The main chamber 160 is provided with a stage 30 that moves in the xdirection, y direction, and 6 (rotation) direction, and an electrostaticchuck is installed on the stage 30. On the electrostatic chuck is placedthe sample 20 itself. Alternatively, the sample 20 set in a pallet orjig is held by the electrostatic chuck.

The main chamber 160 is controlled by a vacuum control system 150 so asto maintain a vacuum in the chamber. The main chamber 160, the transferchamber 161, and the load lock 162 are mounted on a vibration isolationtable 170, and they are configured so that no vibration is transmittedfrom the floor.

The electron column 100 is installed on the main chamber 160. Theelectron column 100 comprises columns of the primary optical system 40and secondary optical system 60, and the detector 70 for detectingsecondary emission electrons, mirror electrons, or the like transmittedfrom the sample 20. A signal from the detector 70 is transmitted to andprocessed by the image processing device 90. Real-time signal processingand delayed signal processing can both be performed. The real-timesignal processing is performed during inspection. When the delayedsignal processing is performed, simply an image is acquired, and thesignal processing is performed later. Data processed by the imageprocessing device 90 is saved to a hard disk, memory, or other recordingmedium. The data can be displayed on a monitor on a console as required.The data to be displayed is, for example, an inspection area, a map ofthe number of foreign materials, the distribution and a map of theforeign material size, foreign material classification, a patch image,or the like. System software 140 is provided to perform such signalprocessing. An electron optical system control power supply 130 isprovided to supply the electron column system with power. The mainchamber 160 may be provided with the optical microscope 110 and theSEM-type inspection device 120.

FIG. 166 shows an example of a configuration in which the electroncolumn 100 which is a projection-type optical inspection device and theSEM-type inspection device 120 are installed in the one and the samemain chamber 160. As shown in FIG. 166, it is very advantageous if theprojection type optical inspection device and the SEM-type inspectiondevice 120 are installed in the one and the same chamber 160. The sample20 is placed on the one and the same stage 30, and the sample 20 can beobserved or inspected by both the projection method and the SEM method.A method of use and advantages of this configuration are as follows.

First, since the sample 20 is placed on the one and the same stage 30,the coordinates are uniquely determined when the sample 20 moves betweenthe projection-type electron column 100 and the SEM-type inspectiondevice 120. Accordingly, when a detection point of the foreign materialor the like is to be located, the two inspection devices can preciselyand easily locate one and the same part.

Suppose that the above-described configuration is not applied. Forexample, the projection-type optical inspection device and the SEM-typeinspection device 120 are separately configured as different devices.The sample 20 is moved between the separate different devices. In thiscase, since it is required to place the sample 20 on different stages30, the two devices are required to align the sample 20 separately. Theseparately performed alignment of the sample 20 would cause a locationerror of 5 to 10 μm for one and the same position. In particular, theerror further increases if the sample 20 does not have any pattern,since the positional reference cannot be located.

In the embodiment, on the other hand, the sample 20 is placed on thestage 30 in the one and the same chamber 160 for the two types ofinspection as shown in FIG. 166. One and the same position can beprecisely located even if the stage 30 moves between the projection-typeelectron column 100 and the SEM-type inspection device 120.Consequently, a position can be precisely located even if the sample 20does not have any pattern. For example, a position can be located with aprecision of 1 μm or less.

Such precise location is significantly advantageous in the followingcase. The foreign material inspection of the sample 20 having no patternis first performed by the projection method. After that, location anddetailed observation (reviewing) of the detected foreign material 10 isperformed by the SEM-type inspection device 120. Since the position canbe located accurately, not only the presence or absence of the foreignmaterial 10 (false detection if absent) can be determined, but alsodetailed observation of the size and shape of the foreign material 10can be performed quickly.

As mentioned above, the separate installation of the electron column 100for foreign material detection and the SEM-type inspection device 120for reviewing would require a great deal of time to locate the foreignmaterial 10. The sample having no pattern would increase the difficulty.Such problems are solved by the embodiment.

In the embodiment, as described above, the foreign material 10 of anultra-micro size can be inspected for with high sensitivity by usingconditions for imaging the foreign material 10 with the projection-typeoptical method. In addition, the projection-type optical electron column100 and the SEM-type inspection device 120 are mounted in the one andthe same chamber 160. Consequently, in particular, inspection for theforeign material 10 of an ultra-micro size of 30 nm or less anddetermination and classification of the foreign material 10 can becarried out with great efficiency and speed. Furthermore, the presentembodiment can be applied to embodiments 1˜28 as well as embodimentswith no number attached.

Another example of the inspection using both projection-type inspectiondevice and SEM will next be described.

In the above description, the projection-type inspection device detectsthe foreign material, and the SEM performs review inspection. However,the invention is not limited to this. The two inspection devices may beapplied to another inspection method. Effective inspection can becarried out by combining the characteristics of each inspection device.Another inspection method, for example, is as follows.

In this inspection method, the projection-type inspection device and theSEM inspect different areas. In addition, “cell to cell” inspection isapplied to the projection type inspection device, and “die to die”inspection is applied to the SEM, so that precise inspection is achievedwith great overall efficiency.

More specifically, the projection-type inspection device performs the“cell to cell” inspection on an area in a die where there are manyrepetitive patterns. The SEM then performs the “die to die” inspectionon an area where there are not many repetitive patterns. Both inspectionresults are combined and one inspection result is obtained. The “die todie” is an inspection for comparing successively obtained images of twodies. The “cell to cell” is an inspection for comparing successivelyobtained images of two cells. A cell is a part of a die.

In the above-described inspection method, the repetitive pattern part isquickly inspected by using the projection method and, on the other hand,the area where there are not many repetitive patterns is inspected bythe SEM with precision and less faults. The SEM is not suited to quickinspection. However, since the area where there are not many repetitivepatterns is relatively small, the SEM does not require too much time forinspection. Consequently, overall inspection time can be reduced. Thisinspection method can thus maximize the merits of the two inspectionmethods to carry out precise inspection in a short inspection time.

Returning now to FIG. 165, a transfer mechanism for the sample 20 willbe described.

The sample 20 such as a wafer and mask is transferred from the load portinto the minienvironment 180, where alignment work is performed. Thesample 20 is transferred to the load lock 162 by the atmospherictransfer robot. The load lock 162 is evacuated from atmospheric pressureto a vacuum by a vacuum pump. When the pressure becomes a certain value(about 1 Pa) or less, the sample 20 is transferred from the load lock162 to the main chamber 160 by the vacuum transfer robot placed in thetransfer chamber 161. The sample 20 is then placed on the electrostaticchuck mechanism on the stage 30.

FIG. 167 shows the inside of the main chamber 160, and the electroncolumn system 100 placed in an upper part of the main chamber 160. Thesame components as those in FIG. 158 are given the same referencenumerals as in FIG. 158 and therefore, an explanation of thosecomponents is omitted.

The sample 20 is placed on the stage 30 that can move in the x, y, z,and θ directions. The stage 30 and the optical microscope 110 performprecise alignment. The projection optical system then uses the electronbeam to perform the foreign material inspection and pattern defectinspection of the sample 20. Here the potential of the sample surface 21is important. A surface potential measurement device that can measure invacuum is installed in the main chamber 160 in order to measure thesurface potential. This surface potential measurement device measuresthe two-dimensional surface potential distribution on the sample 20.Based on the measurement result, focus control is performed in asecondary optical system 60 a that forms an electron image. A focus mapof two-dimensional positions in the sample 20 is created based on thepotential distribution. By using this map, the inspection is carried outwith the focus being changed and controlled during the inspection. Thiscan reduce the defocus and distortion of the image caused by a change inthe surface potential according to location, so that a precise andstable image acquisition and inspection can be carried out.

Here the secondary optical system 60 a is configured to be able tomeasure the detection current of electrons entering the NA aperture 62and the detector 70, and further to be able to place an EB-CCD in theposition of the NA aperture 62. Such a configuration is significantlyadvantageous and efficient. In FIG. 23, the NA aperture 62 and theEB-CCD 65 are mounted on a one-body holding member 66 having openings 67and 68. The secondary optical system 60 a has a mechanism that canseparately and independently perform current absorption with the NAaperture 62 and image acquisition with the EB-CCD 65. In order torealize this mechanism, the NA aperture 62 and the EB-CCD 65 are mountedon the x-y stage 66 that operates in vacuum. Accordingly, positioncontrol and positioning of the NA aperture 62 and the EB-CCD 65 can beperformed. Since the stage 66 is provided with the openings 67 and 68,the mirror electrons and the secondary electrons can go through the NAaperture 62 or the EB-CCD 65.

An operation of the secondary optical system 60 a with such aconfiguration will be described. First, the EBCCD 65 detects the spotshape of the secondary electron beam and the center position of the spotshape. Voltage adjustment is then performed on a stigmator, the lenses61 and 63, and the aligner 64 so that the spot shape becomes circularand minimum. In terms of tl1 is point, conventionally the spot shape andastigmatism at the position of the NA aperture 62 could not be directlyadjusted. The embodiment allows such a direct adjustment to be made,allowing the astigmatism to be corrected precisely.

The center position of the beam spot can also be detected easily.Accordingly, the position of the NA aperture 62 can be adjusted so thatthe center of the opening in the NA aperture 62 is placed in the beamspot position. In terms of this, conventionally the position of the NAaperture 62 could not be directly adjusted. In the embodiment, theposition of the NA aperture 62 can be directly adjusted. Consequently,the NA aperture can be precisely positioned, the aberration in theelectron image decreases, and the uniformity improves. The uniformity ofthe transmittance improves, and an electron image can be acquired with ahigh resolution and uniform gray level.

In the inspection for the foreign material 10, it is important toefficiently acquire a mirror signal from the foreign material 10. Theposition of the NA aperture 62 is very important since it defines thetransmittance and aberration of the signal. Secondary electrons areemitted from the sample surface in a wide angle range following thecosine law, and reach the NA position uniformly with a wide area (e.g.φ3 mm). For this reason, the secondary electrons are insensitive to theposition of the NA aperture 62. In contrast, the reflection angle ofmirror electrons on the sample surface is about the same as the incidentangle of the primary electron beam. The mirror electrons thereforeexhibit a small spread, and reach the NA aperture 62 with a small beamdiameter. For example, the spread area of the mirror electrons is 1/20or less of the spread area of the secondary electrons. For this reason,the mirror electrons are very sensitive to the position of the NAaperture 62. The spread area of the mirror electrons at the NA positionis generally an area of φ10 to φ100 μm. Because of this, it is veryadvantageous and important to determine a position where the intensityof the mirror electrons is the highest and place the center position ofthe NA aperture 62 in the determined position.

In order to achieve such placement of the NA aperture 62 in anappropriate position, the NA aperture 62 in a preferred embodiment ismoved in the x and y directions in the vacuum electron column 100 with aprecision of about 1 μm. The signal intensity is measured with the NAaperture 62 being moved. A position where the signal intensity is thehighest is then determined, and the center of the NA aperture 62 isplaced in the position of the determined coordinates.

The EB-CCD 65 is very advantageously used for the measurement of thesignal intensity. This is because it can get two-dimensional informationon the beam and determine the number of electrons that enter thedetector 70, thereby allowing the signal intensity to be evaluatedquantitatively.

Alternatively, the placement of the aperture may be determined and acondition of the lens 63 existing between the aperture and the detectormay be established so that a conjugate relation between the position ofthe NA aperture 62 and the position of the detection surface of thedetector 70 is achieved. This configuration is also very advantageous.This allows an image of the beam at the position of the NA aperture 62to be formed on the detection surface of the detector 70. The beamprofile at the position of the NA aperture 62 can thus be observed byusing the detector 70.

The NA size (aperture diameter) of the NA aperture 62 is also important.Since the signal area of the mirror electrons is small as describedabove, an effective NA size is about 10 to 200 μm. In addition, the NAsize is preferably a size 10% to 100% larger than the beam diameter.

Discussing in relation to this, the image of the electrons is formedfrom the mirror electrons and the secondary emission electrons. Theabove-mentioned setting of the aperture size can increase the ratio ofthe mirror electrons more. This can increase the contrast of the mirrorelectrons, that is, increase the contrast of the foreign material 10.

Describing in more detail, when the opening in the aperture is small,the secondary emission electrons decrease inversely with the area of theaperture. This reduces the gray level of the normal part. However, themirror signal does not change, and the gray level of the foreignmaterial 10 does not change. Consequently, the contrast of the foreignmaterial 10 can be increased by the amount of decrease in the gray levelof the surroundings, and a higher S/N ratio can be obtained.

The aperture and the like may be configured so that the position of theaperture can be adjusted in the z-axis directions as well as in the xand y directions. This configuration is also advantageous. The apertureis suitably placed in a position where the mirror electrons are mostcondensed. This very effectively reduces the aberration of the mirrorelectrons and cuts down the secondary emission electrons. Consequently,a higher S/N ratio can be obtained.

As described above, the mirror electrons are very sensitive to the NAsize and shape. It is therefore very important to appropriately selectthe NA size and shape in order to obtain a high S/N ratio. An example ofa configuration for such appropriate selection of the NA size and shapewill next be described. The shape of the aperture (opening) of the NAaperture 62 will also be mentioned in the description.

Here the NA aperture 62 is a member (component) having an opening.Generally, the member is sometimes called an aperture, or the opening issometimes called an aperture. In the following aperture-relateddescription, the member is called an NA aperture in order to distinguishthe member (component) from its opening, when FIG. 168 to FIG. 172 arereferred to. An opening in the member is called an aperture. In thefollowing description, symbols 62 and 62 a to 62 d denote NA apertures.Symbols 169, 69, 69 a, and 69 b denote apertures (openings). Theaperture shape generally means the shape of an opening.

FIG. 168 is a reference example, showing a conventional aperture 169. Asshown in FIG. 168, the circular aperture 169 would conventionally beplaced in a fixed position. Consequently, the above-describedappropriate selection of the NA size and shape could not be made.

On the other hand, the sample inspection apparatus according to theembodiment is configured to be able to move the position of the NAaperture 62 two-dimensionally or tl1 ree-dimensionally to set theposition. The movement of the NA aperture 62 may be performed by usingthe x-y stage 66 described in FIG. 167. A suitable aperture may beselected as appropriate from a plurality of apertures and thepositioning may be performed. The one NA aperture 62 may be providedwith a plurality of aperture openings 69, and the NA aperture 62 may bemoved in order to select one of those (this configuration alsocorresponds to the selection from a plurality of apertures). Anothermoving mechanism may be used. For example, the NA aperture 62 may bemoved by a linear motor instead of by the x-y stage 66. A rotationsupport member may support the NA aperture 62, and a common rotary motormay move the position of the NA aperture 62. A specific example of theshape of the opening in the NA aperture 62 will next be described.

FIG. 169 shows an example of the shape of the aperture 69. In FIG. 168,the aperture 69 has an elliptical opening shape. This opening shape iscreated so as to match the intensity distribution of the mirror electronsignal. In this example, the intensity distribution has an ellipticalshape elongated in the y direction according to a measurement result ofthe intensity distribution of the mirror electrons in the aperture. Herethe y direction is the direction in which the deflection is made by theExB filter 46. The y direction corresponds to the direction of theoptical axis of the primary electron beam. This means that theelliptical shape elongated in the y direction is considered to be causedby a deflection component of the ExB filter 46. The aperture shapehaving the major axis in the y direction is therefore very advantageousin order to capture the mirror electrons efficiently. This can increasethe yield of the mirror electrons more than ever before and obtain ahigher S/N ratio (e.g. two times or more). For example, suppose that theintensity distribution of the secondary electron beam extends 100 μm inthe y direction and 50 μm in the x direction (these values are fullwidths at half maximum). The elliptical aperture 69 is selected in arange from 10% to 100% more than the secondary electron beam diameter.For example, the aperture may be selected so that the aperture size is150 μm in the y direction and 75 μm in the x direction.

Configurations of the NA aperture 62 having a plurality of apertures 69will next be described with reference to FIG. 170 to FIG. 173. Here NAapertures 62 a to 62 c are the aperture members, and apertures 69 a arethe openings provided in the aperture members.

FIG. 170 shows an example of a configuration of an NA aperture 62 ahaving a plurality of apertures 69 a. In FIG. 170, the NA aperture 62 ahas two circular apertures 69 a. In this example, the two openings areplaced in positions displaced in ±y directions with respect to thecenter of the intensity of the mirror electrons. The amount ofdisplacement is, for example, about 50 um. This configuration cancapture both mirror electrons scattered on the +y and −y sides from theforeign material 10. This configuration can therefore increase thedifference in the amount of the signal between the scattered mirrorelectrons and the background secondary emission electrons, allowing ahigh S/N ratio to be obtained. The reason of this is that the amount ofthe secondary emission electrons flying in the scattering direction islimited to a small amount. The background therefore decreases, and theS/N ratio can be improved relatively.

FIG. 171 shows an example of a configuration of an NA aperture 62 bhaving four apertures 69 a. In FIG. 171, the four circular apertures 69a are placed symmetrically with respect to the x and y axes. That is,two of the apertures 69 a are placed on the x axis; two of the apertures69 a are placed on the y axis; and the four apertures 69 a arepositioned at the same distance from the center (the origin). In otherwords, the four apertures 69 a are placed at regular intervals aroundthe origin. More simply put, the four apertures 69 a are placed in arhombus shape. Consequently, even when there are mirror electronsscattered in both x and y directions from the foreign material 10, theelectrons can be acquired with a high S/N ratio.

FIG. 172 shows an NA aperture 62 c having four apertures 69 a. Theconfiguration in FIG. 172 is an example different from the configurationin FIG. 171. In FIG. 172, the four circular apertures 69 a areseparately placed in the first to fourth quadrants in the xy plane. Alsoin this example, the four apertures 69 a are placed symmetrically withrespect to the x and y axes, and are placed at the same distance fromthe center (the origin). In other words, the four apertures 69 a areplaced at regular intervals around the origin. Even in the NA aperture62 c of such a shape, the apertures 69 a can be provided in a positionwhere the signal intensity of the mirror electrons is high, and a signalwith a high S/N ratio can be acquired.

As shown in FIG. 171 and FIG. 172, there may be configurations which arethe same in the number of the apertures 69 a but are different in theirarrangement. This allows the appropriate NA aperture 62 b or 62 c to beused depending on the intended use. Consequently, a high S/N ratio canbe acquired in each use.

FIG. 173 shows an example of a configuration of an NA aperture 62 dhaving eight apertures 69 b. As shown in FIG. 173, the number of theapertures 69 b may be more than four. In the NA aperture 62 d shown inFIG. 173, the plurality of apertures 69 b are placed at regularintervals on a circumference around the center of the intensity of themirror electrons. This configuration is advantageous when there aremirror electrons scattering specifically and significantly on theposition of one of the apertures 69 b on the circumference. Such mirrorelectrons can be captured appropriately.

In FIG. 170 to FIG. 173, in terms of the relation between the center ofthe intensity of the mirror electron signal and the apertures 69 a and69 b, the positions of the apertures are off the center of theintensity. However, the invention is not limited to this, and thepositions of the apertures may coincide with the center of theintensity. That is, one of the apertures 69 a or 69 b may be placed soas to coincide with the center of the intensity of the mirror electrons.In this case, the other apertures 69 a or 69 b capture scattered mirrorelectrons. They will be included in an electron image together with themirror electrons in the center of the intensity. Such a composite imageis obtained by the detector 70. In this way, a composite image of theintense mirror electrons and the specifically scattered mirror electronscan be acquired. Consequently, a high S/N ratio can be obtained, and theforeign material 10 distinctive in the scattering direction can bedetected effectively. Additionally, the characteristic in the scatteringdirection can be used to classify the foreign material 10.

Furthermore, in the embodiment, the apertures 69, 69 a, and 69 b of anappropriate shape can also be selected for the landing energy LE to beused. This selection also provides a very advantageous effect. Theintensity distribution of the mirror electrons varies depending on thelanding energy LE. Accordingly, the inspection device of the embodimentmay be configured to use the apertures 69, 69 a, and 69 b having a sizeand shape according to the landing energy LE to be used. This allows theaperture to be adjusted in accordance with the intensity distribution,which is very advantageous. For example, suppose that the mirrorelectrons have an intensity distribution of an elliptical shapeelongated in the y direction, and then the imaging or inspection iscarried out under two different conditions. For example, suppose thatthe landing energy is a first value, i.e. LE=3 eV, in a first imaging orinspection condition. Suppose that the landing energy is a second value,i.e. LE=2 eV, in a second imaging or inspection condition. Here thesmaller the landing energy LE is, the larger the intensity distributionof the mirror electrons becomes at the position of the NA apertures 62and 62 a to 62 d. The NA apertures 62 and 62 a to 62 d are suitablyselected so as to match such a change in the distribution. For example,when the first landing energy is used, the aperture 69 of an ellipseextending 100 μm in the y direction and 50 μm in the x direction may beselected. When the second landing energy is used, the intensitydistribution of the mirror electrons is about two times larger.Accordingly, the aperture 69 of an elliptical shape extending 200 μm inthe y direction and 100 μm in the x direction may be used. Selecting theapertures in this way allows the mirror electrons to be detected veryeffectively.

The Faraday cup and other components described in FIG. 162 will bedescribed again. These components may be installed in the electron beaminspection device in FIG. 167.

FIG. 174 shows the stage 30 in FIG. 167. On the stage 30 are mounted theFaraday cup 31, a reference sample chip 27 having the hollow grooves 25and 25 a, and an EB-CCD 37. Consequently, the uniformity and irradiationposition of the primary electron beam can be precisely monitored, and atemporal variation of the primary electron beam can be preciselymonitored.

In terms of this, there has been conventionally no means to directlymonitor the primary electron beam. For that reason, conventionally theFaraday cup 31 would be placed in a plurality of points on one and thesame sample 20 and an image of the electron beam irradiation would beacquired by means of the Faraday cup 31, on a regular basis. This imagehas been used for an evaluation and adjustment of the beam. Conventionaltechniques, however, could obtain only an image onto which variations ofthe primary optical system 40 and secondary optical system 60 a aresuperimposed. It would be complicated to separate, evaluate, and adjustthe factors of those two optical systems, and the precision would below. The embodiment can solve these problems.

In the embodiment, the distribution of the current density of theprimary electron beam can also be measured precisely. A precise feedbackcan be performed on the electron emission control system comprising thelenses 42 and 45, aligner, and electron gun 41 of the primary opticalsystem. Consequently, a more uniform beam profile can be formed. In aconventional measurement of the distribution of the current density, forexample, a Faraday cup of about φ30 μm in diameter would be used. Themeasurement would then be performed on about five points at 30 μmintervals. In such measurement, the resolution would be limited by thesize of the opening in the Faraday cup 31. The measurement would taketime since the measurement would be performed on a point-by-point basis.As a result, the distribution at the moment of irradiation with theelectron beam could not be measured.

The foreign material inspection device according to the embodiment candirectly measure the beam profile of the primary electron beam and,based on the measurement result, can appropriately adjust the primaryelectron beam.

In such adjustment of the primary electron beam in the embodiment, astandardized sample may be manufactured and used in order to determinethe relation between the size of the foreign material 10 and the signalintensity or S/N ratio. The use of such a sample provides a greatadvantage. For example, standardized microspheres of a known size arescattered on a single film of a sample. Such a sample is preferably usedto calibrate the sensitivity.

FIG. 175 shows the sample 20 on which samples 15 are scattered. Thesamples 15 typically substitute for the foreign material 10. It istherefore preferred to use a sample of a size close to that of theforeign material 10 and of a material close to that of the foreignmaterial 10. For example, the samples 15 are standardized microspheres,whose material is PSL (polystyrene latex). Ultra-fine particles may alsobe used. The sample 20 may be a semiconductor wafer of Si or the like. Afilm may be formed on the semiconductor wafer. The sample 20 may also bea glass substrate on which a film is formed. The film on the sample 20may be either of a conductive film or an insulating film. For example,the film on the semiconductor wafer may be a film of SiO2, Ta, Cu, Al,W, or the like. The film on the glass substrate may be, for example, afilm of Cr, CrN, Ta, TaN, TaBN, TaBO, Si, Al, Mo, or the like.

In FIG. 175, the size of the samples 15 is known. The relation betweenthe size of the samples 15 and the signal intensity or S/N ratio cantherefore be determined by acquiring an image of the samples 15.

FIG. 176 shows a measurement result to be obtained when an image of thesamples 15 shown in FIG. 175 is acquired. FIG. 176 is an example of therelation between the samples 15 and the signal intensity. In FIG. 176,the horizontal axis represents the size of the samples 15, and thevertical axis represents the signal intensity. The vertical axis mayalso represent the S/N ratio. The signal intensity corresponding to thesample size is determined by varying the size of the samples 15 invarious ways. A graph is created from the signal intensity as shown inFIG. 176. Consequently, the relation between the size of the foreignmaterial 10 and the signal intensity or S/N ratio can be grasped.

In the above description, microspheres are used as the samples 15. Anappropriate size of the spheres is particularly 100 nm or less. That is,microspheres o φ1 to φ100 nm are used advantageously. As described up tothis point, the electron beam inspection device and electron beaminspection method according to the embodiment are sensitive even to theultramicro foreign material 10 of the order of nanometers. Theabove-described microscopic samples 15 are advantageously usedparticularly for the inspection for the microscopic foreign material 10.

In terms of this, conventional optical-type foreign material inspectionmethods would have a difficulty in detecting the foreign material 10 ofa size smaller than 100 nm since the resolution would be limited by thewavelength of light. The electron beam inspection device and electronbeam inspection method according to the embodiment can provide anadequate sensitivity and can detect the microscopic foreign material 10.

Referring now to FIG. 177, an embodiment that achieves an appropriatesetting of the landing energy will be described further.

FIG. 177 shows a gray-level characteristic versus beam landing energy inthe electron beam inspection method according to the embodiment. Thisforeign material inspection method may be applied to the sample 20having a solid surface or patterned surface (the solid surface means asurface without a pattern; hereinafter the same shall apply). Theembodiment is characterized in that the characteristic shown in FIG. 177is acquired and the characteristic in FIG. 33 is used to select a regionof the landing energy LE. The gray-level characteristic (the change inthe gray-level value versus the landing energy LE) relates to the typesof electrons to be detected. The types of electrons are shown below:

LE<LEA: mirror electrons;

LEA≦LE≦LEB: a mixture of secondary emission electrons and mirrorelectrons; and

LEB≦LE: secondary emission electrons.

Here, setting LE in a region LEA≦LE≦LEB+5 eV allows an image of a highS/N ratio to be acquired, so that a high-sensitivity defect inspectionand foreign material inspection can be carried out. The reason of thissetting will be described. Suppose, for example, that the foreignmaterial 10 is present on a solid surface such as Si, W, or the like. Inthe embodiment, the foreign material 10 is charged up and forms mirrorelectrons. At this time, it is desired that a background solid surface(a surface without a pattern) has a low gray level, because thisincreases the S/N ratio. In order to reduce the gray level of the solidsurface, the energy conditions for the secondary electron emissionregion and for the mixture region are appropriate. The mixture region isa region in which the mirror electrons and the secondary emissionelectrons are mixed. The mixture region is between the secondaryemission electron region and the mirror electron region, and correspondsto the transition region.

The mixture region is LEA≦LE≦LEB in FIG. 33. It is considered that theforeign material 10 generates mirror electrons and the background sample20 generates secondary emission electrons in this region. In the mirrorelectron region LE<LEA, the background also generates mirror electrons.The gray level of the background therefore increases, so that thedifference in gray level between the foreign material 10 and thebackground decreases. That is, the S/N ratio decreases. In an energyregion in which LE is much larger than LEB, the foreign material 10 alsogenerates secondary emission electrons. The S/N ratio also decreases inthis case.

In order to facilitate the detection of the foreign material 10, it ispreferable to maximize the difference in gray level between themagnified image 81 of the foreign material 10 and the surface image 82of the background sample surface 21. The difference in gray leveldepends on the gray level characteristic versus the landing energy LEshown in FIG. 177. One characteristic curve is shown in FIG. 33. Incontrast, for example, two characteristic curves, a characteristic curveof the foreign material 10 and a characteristic curve of the sample 20in a pure state, are suitably used in the embodiment. In the embodiment,the two characteristics may be compared, and a landing energy LE in arange in which the difference in gray level is the largest may be used.This allows the landing energy to be determined appropriately.

Discussing in relation to the above description, the energy range inwhich the difference in gray level is large varies depending on thecombination of the characteristic curve of the foreign material 10 andthat of the sample surface 21. Accordingly, the landing energy issuitably set by using the characteristic curves of an object to bedetected.

According to past experimental experiences, LE in the regionLEA≦LE≦LEB+5 eV is very advantageously used and provides a greatadvantage. The method and configuration that employs this energy regionmay be applied to any method and configuration described up to thispoint to the extent possible. Consequently, a high S/N ratio can beacquired, and high sensitivity and high speed defect inspection andforeign material inspection can be carried out.

Referring now to FIG. 178, the landing energy LE of the primary electronbeam efficient in detection of or inspection for the foreign material 10will be described in further detail. FIG. 178 shows a relation betweenthe landing energy LE of the electron beam of the primary system and thegray level of an image. In FIG. 178, the gray-level characteristic ofthe sample 20 and that of the foreign material 10 are shown as therelation between the sample 20 and the foreign material 10.

As referred to in the description of FIG. 177, the region in which thelanding energy LE is smaller than LEA indicates the mirror electronregion. The mirror electron region is an energy region in which almostonly mirror electrons are detected from the normal part where theforeign material 10 is not present on the sample 20.

The region in which the landing energy LE is larger than LEB indicatesthe secondary electron region. The secondary electron region is a regionin which almost only secondary electrons are detected from the normalpart of the sample 20. Here, for the sake of simplicity, secondaryelectrons are given attention and the term secondary electron region isused. More specifically, the region is the secondary emission electronregion, and secondary emission electrons are generated. As previouslydescribed, the secondary emission electrons may include secondaryelectrons, reflected electrons, and backscattered electrons.

The region in which the landing energy LE is LEA or more but notexceeding LEB is the mixture region. The mixture region means a mixtureregion in which both mirror electrons and secondary electrons aredetected from the normal part of the sample 20. The mixture region isthe transition region between the mirror electron region and thesecondary electron region.

As described above, the landing energy LE of the electron beam of theprimary system with which irradiation is performed is preferably set inthe energy region LEA≦LE≦LEB or LEA≦LE≦LEB+5 eV. This will be describedin more detail with reference to FIG. 178.

FIG. 178 shows a change in the gray-level DN versus the landing energyLE of the primary electron beam, for each of the foreign material 10 andthe normal part on the sample 20. The gray-level DN (digital number)corresponds to the number of electrons to be detected by the detector70. If the contact resistance between the foreign material 10 and thesample 20 is high or if the foreign material 10 is charged, the foreignmaterial 10 exhibits a change in gray level different from that of thesurrounding normal part. This is because a potential change occurs inthe foreign material 10, allowing mirror electrons to be generatedeasily. According to the findings made by the inventors, the range fromLEA to LEB has often been seen to be from −5 eV to +5 eV. As describedabove, the foreign material 10 generates mirror electrons even when thelanding energy LE of the primary electron beam is high, as compared tothe normal part (here the mirror electrons may be mixed with thesecondary electrons). The range from LEA to LEB+5 eV is thereforesuitable as the region of the landing energy LE to be used when theimaging of or inspection for the foreign material 10 is carried out. Forexample, suppose that LEA to LEB is −5 eV to +5 eV. In this case, theregion of the landing energy LE is very preferably from −5 eV to +10(:5+5) eV.

The landing energy range “from LEA to LEB+5 eV” is effective forsubstrates of all types, regardless of the material of the substrate.For example, the landing energy range “from LEA to LEB+5 eV” iseffective for a substrate on which a pattern or the like is formed, andalso for a substrate or the like on the surface of which a foreignmaterial is present. Moreover, this LE range is effective regardless ofthe material of the substrate and foreign material. For example, thelanding energy range “from LEA to LEB+5 eV” is also suitably applied toobservation of a glass substrate. This allows a good image to beobtained.

Here the reason why the foreign material 10 can be imaged with a highcontrast is clear from FIG. 178. As shown in FIG. 178, the change inbrightness is different between the foreign material 10 and thesurrounding normal part. The foreign material 10 generates mirrorelectrons at a higher landing energy LE (=LEB+5 eV) than the normalpart. For this reason, the difference in gray level between the foreignmaterial 10 and the normal part, ADN, can be secured large asillustrated. For example, suppose that the gray-level DN of the normalpart is 50 DN and the variation in brightness (the noise) of the normalpart is 3 DN. Suppose also that the gray-level DN of the foreignmaterial 10 is 100 DN. In this case, the difference in gray level isΔDN=50 DN (=100 DN−50 DN). The S/N ratio is therefore 50/3:16.7. In thisway, a high S/N ratio can be obtained. This is exactly theabove-described phenomenon that occurs in the region of the landingenergy LE, from LEA to LEB+5 eV. The use of this phenomenon allows theimaging and inspection to be carried out with a high contrast. Otherregions of the landing energy LE can not achieve the state where onlythe foreign material 10 generates mirror electrons, and therefore alsocannot achieve a high contrast between the foreign material 10 and thesurrounding normal part as described above. The foreign material 10 istherefore preferably detected in the range LEA≦LE≦LEB+5 eV. In addition,with regards to the descriptions in the present example, an adjustmentmethod, that is, a method for adjusting, controlling and determining therelative relationship between mirror electrons (mirror center MC) andthe NA aperture position (x, y direction) with respect to the centerposition of a crossover of secondary emission electrons at an NAlocation described in the embodiments related to FIGS. 44˜50 is used. Inthis way, it is possible to efficiently and effectively obtain a highcontrast and S/N of a defect.

While there have been described what are at present considered to bepreferred embodiments of the invention, it will be understood thatvarious modifications and variations may be made thereto, and it isintended that appended claims cover all such modifications andvariations as fall within the true spirit and scope of the invention.

The present invention can inspect for the presence of foreign materialson a sample such as a semiconductor wafer using an electron beam, or beused in an electron beam inspection device which inspects for presenceof a defect. Furthermore, the present embodiment can be applied to theembodiments 1˜28 and also to embodiments with no number attached.

Thirtieth Embodiment Platform

An example of platform used in the inspection device and inspectionmethod of the present invention is explained.

In the present embodiment, an example which uses an inspection deviceand inspection method of the present invention for a mask (EUV mask,NIL), and parts (inversion unit, rotation unit, palette loading unit,neutralization unit) which are different to the inspection device andinspection method used for a wafer in the embodiments described aremainly explained.

Referring to FIG. 179 and FIG. 180, a mask in a cassette such as a SMIFis transferred by an atmosphere transfer robot. Either the surface andrear surface of the mask is inspected. In addition, the direction forsetting the mask is selected and inspection is performed. If the mask isin the same state as in the cassette then inversion is not necessary. Inthe case of changing the mask direction 90° or 180° for example, andperforming an inspection, a direction in the rotation unit is selectedas and set. If the mask is in the same state as in the cassette thenthis process is not necessary. Following this, the mask is arranged inthe palette loading unit by the robot. The mask is mounted on thepalette and the palette mounted with the mask is transferred. Whenmounting on the palette, a positioning mechanism is used for example, adirection adapter which determines the direction for arranging the maskat opposite corners. In this way, a rough direction is determined, forexample, ±1˜10 mrad (radian). The neutralization unit neutralizes acharge in the mask. When there is static electricity or when the mask isaffected by light or electron or electrical effects in a previousprocess or inspection, a charge up remains on the mask surface.Neutralization is performed in the atmosphere transfer part in order toremove this charge, maintain a homogeneous surface potential state andperform a stable inspection. X ray irradiation, UV irradiation or ionirradiation are used for neutralization. Following this, the mask istransferred to an LL chamber. In the LL chamber a vacuum exhaust isperformed to obtain a vacuum state. At this time, a slow exhaust isinitially performed, and by raising the exhaust speed any attachedparticles are reduced and the time for forming a vacuum state isreduced. A CCD camera is arranged in the LL chamber in order tocalculate the amount of alignment correction of the mask. In this way,the extent of any rotation direction misalignment is measured, and acorrection amount of stage rotation is determined. If this is an amountwhich exceeds a correction amount, the mask is again returned to thepalette loading unit, and the mask is reset. A vacuum, transfer robot islocated in a transfer chamber. By arranging the mask in a vacuum statechamber, the attachment of particles to the robot is prevented and theproduction of dust from the robot is prevented. When the LL chamberreaches a defined vacuum level, a gate valve is opened and the paletteand mask are transferred by the vacuum transfer robot to a stage in themain chamber. The stage can perform triaxial control x, y, θ. In orderto maintain accuracy, the θ stage rotation angle is small, atmaximum±1˜3°. This may be within a range achievable by pre-alignment. Inthis way, the θ stage accuracy and rigidity can be increased. A largeclearance is required when a rotation angle is large, and angle controlaccuracy and rigidity deteriorate. The palette arranged in the stage isan electrostatic chuck and is fixed. A Faraday cup, correction sampleand reference sample are located on the stage. A stage location detectorperforms location detection and control with a laser interferometer thesame as in the case of a wafer. Furthermore, the present embodiment canbe applied to the embodiments 1˜29 and also to embodiments with nonumber attached.

Thirty First Embodiment

Another example in foreign material inspection in the inspection deviceand inspection method of the present invention is explained.

(EO Adjustment Method)

As described in the EO adjustment method of a pattern above, bymeasuring the EO conditions used in foreign material inspection, thedistribution of a beam which arrives at an NA location and controllingthe location of mirror electrons it is possible to realize a foreignmaterial inspection with a high level of sensitivity. In an example of apattern inspection, FIG. 181 is referred to which can adjust anddetermine an observation of abeam at an NA location and irradiationangles θ, α. In the case of foreign material inspection, the surface ofan object to be inspected is often solid (flat), that is, the surfaceoften does not have a pattern. Consequently, accuracy is not requestedwith respect to α. However, it is necessary to align the coordinates ofa detected defect. At this time, it is possible to similar determine thecorrelation with an NA and pattern inspection.

In particular it is effective to distance the mirror electron locationfrom the CO center of secondary emission electrons in order to increasesensitivity to an ultrafine foreign material with a size of 5˜30 nm.That is, it is effective to increase the irradiation electron angle θ.(when a perpendicular axis from a sample is given as z axis, 0°). Thisis because when irradiating with a larger angle than a perpendicularangle, it is easy to be affected by the non-uniformity of a surfacepotential. That is, a potential difference of a surface with respect toan energy in a z direction provides an influence, however, the closerirradiation is performed in a horizontal direction rather thanperpendicular direction the greater are the effects on the speedcomponent of a z direction and therefore a large difference is producedwith the trajectory of an electron in a periphery normal part. Anothercause is that it is easy for a non-uniform charge to be produced in aforeign material. Simply speaking, a shadow of an irradiated beam caneasily be formed, the potential difference between a part which isirradiated and parts which is not irradiated becomes larger, and a rapidpotential distribution change is formed in the vicinity of a foreignmaterial. Therefore, a trajectory may easily be changed due to theseeffects. Sensitivity is improved due to these effects. This concept isshown in FIG. 182. An experimental result shows that an irradiationangle of about 10˜30° is effective when inspecting with a highsensitivity in a detection of a foreign material with a size of 5˜30 nm.Alternatively, at this time, as much as possible a mirror electronsignal from a normal part is not obtained. An NA location is determinedso that only mirror electrons from the foreign material are obtained.Specifically, an NA is arranged between the CO center of the secondaryemission electrons and the MC location. In addition, preferably, the NAis set at a location slightly away so that the MC location (mirrorelectron location) is not affected. In addition, more preferably, thedistance between the MC end part and NA end part is set to 1˜100 μm andmore preferably, 10˜50 μm. This is because when performing an inspectionof a large area, the MC location varies for various reasons andtherefore it is important to maintain the above described distance inorder to achieve a stable and high S/N foreign material detection. Inaddition, although any direction may be the MC direction a signal caneasily by produced from that direction. That is, when a foreign materialis a sphere, an elliptical signal in that direction is obtained. Thismeans that an enlarged signal is obtained. That is, since a signal isobtained with a larger size than the size of a foreign material, it ispossible to perform detection with a Px size larger than the size of aforeign material. This is very effective for throughput of an ultrafineforeign material inspection in particular. For example, when the foreignmaterial size is 10 nm, it is possible to perform a detection at 100 nmPx in the present invention. A throughput difference of ×100 times isproduced compared to the case where 10 nm Px is used. In the presentinvention, it is possible to use a pixel size of ×5˜50 times the minimumsize of the foreign material to be detected. In addition, in particular,it is effective to use ×2˜×10 in the case of a difficult ultrafineforeign material size of 5˜30 nm. Because a Px size of ⅓˜ 1/10 the sizeof a foreign material is necessary in the case of detecting a foreignmaterial using a SEM method, a difference with the present invention of×6˜×100 is produced just in terms of Px size which is a significantthroughput difference. In addition, since there is a limit to detectingforeign materials of a ½ wavelength size using a light method, detectionof ultrafine foreign materials which is the object of this invention cannot be performed.

In addition, with regards to direction, when the MC and NA are arrangedin a Y direction or X direction, a symmetrical signal can be obtainedwith respect to the x and y axis, and asymmetric when diagonal. Theseare used separately by selecting the better sensitivity according to theobject sample or foreign material. Furthermore, the present embodimentcan be applied to the embodiments 1˜30 and also to embodiments with nonumber attached.

Thirty Second Embodiment

In the present embodiment, an example of an NA (numerical aperture) usedin the inspection device and inspection method of the present inventionis explained.

(NA Shape)

In a pattern inspection and foreign material inspection, it is moreeffective to use an NA with the shape shown in FIG. 183 and FIG. 184compared with a normally used NA having a round shaped hole. A highcontrast and S/N and electron amount can be obtained as well as anincrease in sensitivity and throughput.

In a pattern inspection, a vertical and horizontal pattern sometimes hasa different contrast in a y direction and x direction. When a + shapedhole is used in this case, it is possible to combine data of an electronsignal with a strong vertical contrast and an electron signal with astrong horizontal contrast, increase the amount of electrons at a highcontrast and obtained a high S/N.

A data of a stronger vertical signal is obtained using a slit.Alternatively, it is effective when obtaining electron data havingcharacteristic due to a direction such as obtaining a lot of data in ahorizontal direction. In the case of a pattern, for example, amisalignment is sometimes produced at a cross over point (Cox, Coy) inan x and y direction such as ExB. At this time, the amount of electrondata and aberration in an y direction is measured, using a slit in whichhas a hole is longer in the y direction at a COx in the x direction, andthe amount of electron data and aberration in an x direction is measuredusing a slit in which has a hole is longer in the x direction at a COyin the y direction. In this way, the amount of electrons and aberrationis controlled, a high contrast and S/N can be obtained, and because theamount of electrons can be increased, sensitivity and throughput can beimproved compared to a round shaped hole.

A sensitivity improvement of ×1.4˜×5 and an increase in the amount ofelectrons of ×1.5˜10 can be obtained with the NA described above.

In addition, the NA shape shown in FIG. 184 is particularly effectivewhen used in a foreign material inspection, a shape A having a hollowpart and a slit. When inspecting a foreign material, it is effective toarrange an NA at a location which does not affect a mirror electron.However, when arranging the NA at a location near the MC location wherethe mirror electron has a strong intensity, an S/N having a high foreignmaterial signal can sometimes be obtained. At this time, it is effectiveto use the NA as shown in FIG. 184. Because a round shaped hole is abump shaped hole, a lot of electron data near an MC can not be obtainedand when the location of an MC varies the effects are soon received. Theshape shown in FIG. 184 is provided as a method of solving this problem.It is easy to bring closer to an MC if this shape has a hollow part andit is possible to obtain a lot of electron data near the MC. Inaddition, because a hollow shape along the MC shape or the hole shape ofa slit (line shape) is on the side close to an MC, even if the MClocation varies it is possible to set the hole at a distance where noeffects are received. It is also possible to obtain more peripheryelectron data than a round shape of a bump shaped hole. The fact thatthe brightness of only a foreign material increases by a mirror electronis used within electron data with a mixture of a mirror electron signalof a foreign material and a secondary emission electron signal of anormal periphery part. At this time, when MC electron data is mixed,mirror electrons are added to the entire image region, the grey level(same as a difference in brightness, difference in amount of electrons)between a foreign material and periphery decreases and an S/N alsodecreases.

A conceptual view of this state is shown at the bottom FIG. 184 whichshows an example of the MC and NA arrangement. The MC is normally around shape. At this time, each NA is arranged so that a hole end partis located at the same distance L1 from the end part of the MC. Inaddition, the width and diameter (L2) of the hole are the same. At thistime, because the hollow type and slit type holes have a large area andbecause the area at a location near an MC is also large it is possibleto obtain an electron signal near the MC.

In addition, FIG. 185 and FIG. 186 are examples of the locationrelationship for arranging an MC and NA. It is possible to use thisexample in a pattern observation and foreign material inspection usingthis type of location relationship. In addition, it is possible andeffective to use the examples in embodiment 29 described above withregards to the conditions of an irradiated electron beam and prechargeconditions.

Thirty Third Embodiment

In the present embodiment, modified embodiments of the inspection deviceof the present invention shown in FIG. 8 are explained. Apart fromarranging an electrode 725, the modified embodiment is the same as theinspection device of the present invention shown in FIG. 8 andtherefore, repeated explanations are omitted. As is shown in FIG. 187,when a voltage applied to an electrode 725 is 4000V˜−400V when there isa via b on a wafer, it is possible to obtain an electric field of theelectron beam irradiation surface of a wafer of 2.0 kV˜−0.2 kV/mm (−shows that the wafer side is a high potential). In this way it ispossible to increase or decrease the electrical field intensity(perpendicular direction, Z direction from the surface) of a samplesurface. That is, it is possible to reduce the electrical fieldintensity in the case of a sample which is easily discharged so that itdoes not discharge. In this state, discharge does not occur between anobject lens system 724 and a wafer W, and a defect inspection of thewafer W can be performed. However, the emission efficiency of electronsslightly decreases. Therefore, a predetermined detection sensitivity isobtained by an accumulation calculation or averaging process of adetection result comprised of four detection results obtained byperforming a series of four operations for detecting a photoelectronwhich is irradiated.

In addition, it is possible to use a relatively high electrical fieldintensity in the case where the wafer does not include a via b. It ispossible to perform a defect inspection of a wafer W without dischargeoccurring between an object lens system 724 and the wafer W even when avoltage provided to the electrode 725 is +3000V. In this case, it ispossible to increase a pickup electric field increases due to thevoltage provided to the electrode 725 and reduce aberrations in theobject lens, and therefore, it is possible to improve resolution andachieve a high contrast and S/N. Consequently, an inspection can beperformed with a high sensitivity and throughput.

(Electrode)

A roughly symmetrically shaped electrode 725 with respect to theirradiation optical axis of an electron beam is arranged between theobject lens 724 and wafer W. An example of the shape of the electrode725 is shown in FIG. 188 and FIG. 189.

FIG. 188 and FIG. 189 are perspective views of the electrode 725, FIG.188 is a perspective view showing the case where the electrode has anaxisymmetrically cylinder shape, and FIG. 189 is a perspective viewshowing the case where the electrode 725 has an axisymmetrically discshape.

In the present embodiment, as is shown in FIG. 188, the electrode 725 isexplained with a cylinder shape. However, the disc shape shown in FIG.189 may also be used if it is roughly symmetrical with respect to theirradiation optical axis of an electron beam.

Furthermore, a lower predetermined voltage (negative potential) than thevoltage (since the voltage in the present embodiment is grounded thepotential is 0) applied to the wafer W is applied by the power supply726 in order to generate an electric field for preventing dischargebetween the object lens 724 and the wafer W. The potential distributionbetween the wafer W and the object lens 724 is explained referring toFIG. 190.

FIG. 190 is a graph which shows the voltage distribution between thewafer W and the object lens 724.

In FIG. 190, a voltage distribution from the wafer W up to the locationof the object lens 724 is shown with the location at the irradiationoptical axis of an electron beam as the horizontal axis.

The voltage distribution from the object lens 724 up to the wafer W in aconventional electron beam device without the electrode 725 changessmoothly up to the grounded wafer when the voltage applied to the objectlens 724 is a maximum value ([conventional] shown in FIG. 190).

On the other hand, in the electron beam device of the presentembodiment, because the electrode 725 is arranged between the objectlens 724 and the wafer W and a lower predetermined voltage (negativepotential) than the voltage applied to the wafer W is applied by thepower supply 726, the electric field of the wafer W weakens ([includingelectrode] in FIG. 190).

Therefore, in the electron beam device of the present embodiment, anelectric field does not crowd near the via b of the wafer b and does notbecome a high electrical field. Then, even if an electron beam isirradiated to the via b and secondary emission electrons are emitted,because these emitted secondary electrons are not accelerated in aprocess for ionizing a residual gas, it is possible to prevent adischarge between the object lens 724 and the wafer W.

In addition, because it is possible to prevent discharge between theobjective lens 724 and the via b, there is no discharge damage to thepattern of the wafer W etc.

In addition, in the embodiment described above, while it is possible toprevent discharge between the object lens 724 and the wafer W which hasa via b and therefore a negative voltage is applied to the electrode725, the detection sensitivity in the detector 726 of a secondaryelectron sometimes decreases depending on the size of the negativepotential. Therefore, when detection sensitivity decreases, as describedabove, an electron beam is irradiated, a series of operations fordetecting secondary electrons is performed over a plurality of times,and a predetermined detection sensitivity (signal S/N ratio) can beobtained by an accumulation calculation or averaging process of theplurality of detection results obtained.

In the present embodiment, an example of detection sensitivity isexplained as a noise with respect to signal ratio (S/N ratio).

Here, the secondary electron detection operation described above isexplained while referring to FIG. 191.

FIG. 191 is a flowchart which shows the secondary electron detectionoperation of the electron beam device.

First, secondary electrons from a sample to be inspected are detected bythe detector 761 (step 1). Next, a judgment is performed whether asignal to noise ratio (S/N ratio) is a predetermined value or more (step2). In step 2, in the case where the signal to noise ratio is apredetermined value or more, detection of secondary electrons by thedetector 761 is sufficient and a secondary electron detection operationis complete.

On the other hand, in step 2, in the case where the signal to noiseratio is less than a predetermined value, an electron beam is irradiatedand a series of operations for detecting secondary electrons isperformed 4N times, and an averaging process is performed (step 3).Here, the initial value of N is set at [1], therefore, a detectionoperation of secondary electrons in step 3 is first performed fourtimes.

Next, [1] is added to N and a counted up (step 4), and in step 2, ajudgment is made again whether the signal to noise ratio is apredetermined value or more. Here, in the case where the signal to noiseratio is less than a predetermined value, the process moves to step 3and the detection operation of the secondary electrons is performed 8times. Then, N is counted up and the steps 2˜4 are repeated until thesignal to noise ratio is the predetermined value or more.

In addition, in the present embodiment, a method of preventing dischargeto a wafer with a via b by applying a lower predetermined voltage (anegative voltage) to the electrode 725 than the voltage applied to thewafer W was explained. However, the detection efficiency of secondaryelectrons sometimes decreases.

Therefore, in even in the case of a sample to be inspected is a typesuch as a wafer with no via, where a discharge between itself and anobject lens 724 is not easily produced, it is possible to control avoltage applied to the electrode 725 so that the detection efficiency ofsecondary electrons in the detector 761 increases.

Specifically, even in the case where a sample to be inspected isgrounded, the voltage applied to the electrode 725 is made a higherpredetermined voltage than the voltage applied to the sample to beinspected, for example, +10V. In addition, at this time, the distancebetween the electrode 725 and the sample to be inspected is a distancewhere discharge is not easily generated between the electrode 725 andthe sample to be inspected.

In this case, secondary electrons which are produced by irradiation ofan electron beam to a sample to be inspected are accelerated to theelectron beam source 721 side by an electric field generated by thevoltage applied to the electrode 725. In addition, because the secondaryelectrons are accelerated and convergence effects are received at theelectron beam source 721 side by an electric field generated by thevoltage applied to the object lens 724, it is possible to irradiate manysecondary electrons to the detector 761 and increase the detectionefficiency.

In addition, because the electrode 725 is axisymmetrical, a lens effectwhich converges an electron beam irradiated to a sample to be inspectedis produced. Therefore, it is possible to further narrow a primaryelectron beam due to the voltage applied to the electrode 725. Inaddition, because it is possible to further narrow a primary electron bythe electrode 725, it is possible to form an object lens system witheven fewer aberrations by combining with the object lens 724. These lenseffects can be obtained to a certain extent as long as the electrode 725is roughly axisymmetrical.

According to the electron beam device of the present example describedabove, because an electrode which controls an electric field in anelectron beam irradiated surface of a sample to be inspected is arrangedbetween the sample to be inspected and an object lens, it is possible tocontrol the electric field between the sample to be inspected and theobject lens.

In addition, because an electrode which is arranged between a sample tobe inspected and an object lens has a roughly axisymmetrical shape withrespect to the irradiation axis of an electron beam and weakens anelectric field intensity at an electron beam irradiated surface of asample to be inspected, it is possible to remove a discharge between thesample to be inspected and the objected lens.

In addition, because a reduction of a voltage applied to an object lensdoes not change, secondary electrons pass efficiently through the objectlens and therefore it is possible to improve detection efficiency andobtain a signal with a good S/N ratio.

In addition, it is possible to control a voltage for weakening anelectric field intensity in an electron beam irradiated surface of asample to be inspected according to the type of sample to be inspected.

For example, when the sample to be inspected is a sample of a type wheredischarge occurs easily between itself and an object lens, the voltageof an electrode is changed and discharge can be prevented by furtherweakening an electric field intensity in an electron beam irradiatedsurface of a sample to be inspected.

In addition, the voltage applied to an electrode is changed depending onthe presence of a via in a semiconductor wafer. That is, it is possibleto change a voltage for weakening an electric field intensity in anelectron beam irradiated surface of a sample to be inspected.

For example, in the case where a sample to be inspected is of a typewhere discharge occurs easily between itself and an object lens, it ispossible to prevent discharge particularly in a via or via periphery bychanging an electric field with an electrode and weakening an electricfield intensity in an electron beam irradiated surface of a sample to beinspected.

In addition, because a discharge between a via and an object lens can beprevented, there is no discharge damage to a pattern etc of asemiconductor wafer.

In addition, because a potential provided to an electrode is lower thana charge provided to a sample to be inspected, it is possible to weakenan electric field intensity in an electron beam irradiated surface of asample to be inspected and prevent discharge to the sample to beinspected.

In addition, because the potential provided to an electrode is anegative potential and the sample to be inspected is grounded, it ispossible to weaken an electric field intensity in an electron beamirradiated surface of a sample to be inspected and prevent discharge tothe sample to be inspected. Furthermore, the present embodiment can beapplied to the embodiments 1˜33 and also to embodiments with no numberattached.

Thirty Fourth Embodiment

In the present embodiment, a modified embodiment in the inspectiondevice of the present invention shown in FIG. 8 is explained. An imagingdevice arranged with a precharge unit of the present embodiment isexemplary shown in FIG. 192. The imaging device 1 is arranged with aprimary optical system 72, secondary optical system 74, detection system76, and a charge control means 840 which uniformalizes or reduces acharge to an object. In the present embodiment an explanation of thesame structure as embodiment 1 described above is omitted.

In this example, the charge control means 840 which uniformalizes orreduces a charge to an object includes an electrode 841 which is broughtnear to and arranged between an object W and an electrostatic lens 724of a primary optical system nearest to the object W, a switch 842 whichis electrically connected to the electrode 841, a voltage generator 844which is electrically connected to one terminal 843 or the switch 842,and a charge detector 846 which is electrically connected to the otherterminal 845 of the switch 842. The charge detector 846 includes a highimpedance. A timing generator 849 provides operation timing commands toa CCD 762 and image processing part 763 of the detector system 76, theswitch 842 of the charge control means 840, and the voltage generator844, and charge detectors 846 and 848. Furthermore, the presentembodiment can be applied to the embodiments 1˜33 and also toembodiments with no number attached.

Thirty Fifth Embodiment Device Manufacturing Method

Next, an embodiment of a method of manufacturing a semiconductor deviceaccording to the present invention will be described with reference toFIG. 193 and FIG. 194.

FIG. 193 is a flow chart illustrating an embodiment of a method ofmanufacturing a semiconductor device according to the present invention.Manufacturing processes of this embodiment include the following mainprocesses:

(1) a wafer manufacturing process for manufacturing a wafer (or a waferpreparing process for preparing a wafer) (Step 1400);(2) a mask manufacturing process for manufacturing masks to be usedduring the exposure (or mask preparing process for preparing masks)(Step 1401);(3) a wafer processing process for performing any processing treatmentnecessary for the wafer (Step 1402);(4) a chip assembling process for cutting out those chips formed on thewafer one by one to make them operable (Step 1403); and(5) a chip inspection process for inspecting finished chips (Step 1404).

The respective main processes are further comprised of severalsub-processes.

Among these main processes, the wafer processing process set forth in(3) exerts a critical effect on the performance of resultantsemiconductor devices. This process involves sequentially laminatingdesigned circuit patterns on the wafer to form a large number of chipswhich operate as memories, MPUs and so on. The wafer processing processincludes the following sub-processes:

(A) a thin film forming sub-process for forming dielectric thin filmsserving as insulating layers and/or metal thin films for forming wiringsor electrodes, and the like (by using CVD, sputtering and so on);(B) an oxidization sub-process for oxidizing the thin film layers andthe wafer substrate;(C) a lithography sub-process for forming a resist pattern by usingmasks (reticles) for selectively processing the thin film layers and/orthe wafer substrate;(D) an etching sub-process for processing the thin film layers and/orthe wafer substrate in accordance with the resist pattern (by using, forexample, dry etching techniques);(E) an ion/impurity injection/diffusion sub-process;(F) a resist striping sub-process; and(G) a sub-process for inspecting the processed wafer;

As can be appreciated, the wafer processing process is repeated a numberof times depending on the number of required layers to manufacturesemiconductor devices which operate as designed.

FIG. 194A is a flow chart illustrating the lithography sub-process whichforms the core of the wafer processing process in FIG. 193. Thelithography sub-process includes the following steps:

(a) a resist coating step for coating a resist on the wafer on whichcircuit patterns have been formed in the previous process (Step 1500);(b) an exposing step for exposing the resist (Step 1501);(c) a developing step for developing the exposed resist to produce aresist pattern (Step 1502); and(d) an annealing step for stabilizing the developed resist pattern (Step1503).

Since the aforementioned semiconductor device manufacturing process,wafer processing process and lithography process are well known, nofurther description is required.

When the defect inspection method and defect inspection apparatusaccording to the present invention are used in the inspectionsub-process set forth in (G), any semiconductor devices, even thosehaving miniature patterns, can be inspected at a high throughput, sothat a total inspection can also be conducted, thereby making itpossible to improve the yield rate of products and prevent defectiveproducts from being shipped.

Inspection Procedure

An inspection procedure in the inspection process (G) stated above isexplained as follows.

Generally, since an inspection apparatus using an electron beam isexpensive and the throughput thereof is rather lower than that providedby other processing apparatuses, this type of inspection apparatus iscurrently applied to a wafer after an important process (for example,etching, film deposition, or CMP (chemical and mechanical polishing)flattening process) to which it is considered that the inspection isrequired most.

A wafer to be inspected is, after having been positioned on anultra-precise X-Y stage through an atmosphere transfer system and avacuum transfer system, secured by an electrostatic chucking mechanismor the like, and then a detect inspection is conducted according to aprocedure as shown in (FIG. 194B). At first, if required, a position ofeach die is checked and/or a height of each location is sensed, andthose values are stored. In addition, an optical microscope is used toobtain an optical microscope image in an area of interest possiblyincluding defects or the like, which may also be used in, for example,the comparison with an electron beam image. Then, recipe informationcorresponding to the kind of wafer (for example, after which process theinspection should be applied; what is the wafer size, 20 cm or 30 cm,and so on) is entered into the apparatus, and subsequently, after adesignation of an inspection place, a setting of an electron opticalsystem and a setting of an inspection condition being established, adefect inspection is typically conducted in real time whilesimultaneously obtaining the image. A fast data processing system withan algorithm installed therein executes an inspection, such as thecomparisons between cells, between dies or the like, and any resultswould be output to a CRT or the like and stored in a memory, if desired.Those defects include a particle defect, an irregular shape (a patterndefect) and an electric defect (a broken wire or via, a bad continuityor the like); and the fast data processing system also can automaticallyand in realtime distinguish and categorize the defects according totheir size, or whether they are a killer defect (a critical defect orthe like which disables a chip). The detection of the electric defectmay be accomplished by detecting an irregular contrast. For example,since a location having a bad continuity would generally be positivelycharged by an electron beam irradiation (about 500 eV) and thereby itscontrast would be decreased, the location of bad continuity can bedistinguished from normal locations. The electron beam irradiation meansin that case designates an electron beam source (means for generatingthermal electron, UV/photoelectron) with lower potential (energy)arranged in order to emphasize the contrast by a potential difference,in addition to the electron beam irradiation means used for a regularinspection. Before the electron beam being irradiated against theobjective region for inspection, the electron beam having that lowerpotential (energy) is generated and irradiated. In the case of aprojecting method in which the object can be positively chargedparticles by the irradiation of the electron beam, the electron beamsource with lower potential is not necessarily arranged separately,depending on the specification of the system for the method. Further,the defect may be inspected based on the difference in contrast (whichis caused by the difference in flowability of elements depending on theforward or backward direction) created by, for example, applying apositive or negative potential relative to a reference potential to awafer or the like. This electron beam generation means may be applicableto a line-width measuring apparatus and also to an aligning accuracymeasurement.

It is possible to apply all of the embodiments described above during aninspection and inspection process required in the processes describedabove. In addition, it is also possible to apply the embodiments to allof the device systems which include the functions, mechanisms andcharacteristics of FIG. 1˜FIG. 25 described above. In this way, it ispossible to perform a very efficient inspection in a manufacturingprocess of a wafer or mask. Furthermore, the present embodiment can beapplied to the embodiments 1˜34 and also to embodiments with no numberattached.

Thirty Sixth Embodiment Inspection of a HDD Substrate, Head Element

The present invention can also be applied to an inspection of a HDDsubstrate as well as a wafer and exposure mask. While applicationexamples are described below, the effects and operations are the same asthat for a semiconductor wafer or mask.

For example, in a HDD substrate, it is usual to arrange a magnetic toplayer on a glass or ceramic substrate and above this is arranged a thinlubricating layer. Two types of inspection can be performed on thissubstrate. One is an inspection of attached foreign materials orparticles and damage when manufacturing the substrate and the other isan inspection of defects of a film quality when forming a surface.

It is no longer possible to normally form a magnetic film on a substratewhen an aluminum or glass substrate itself is damaged or when foreignmaterials or particles are attached after manufacturing or cleaning.This is because the level of planarization deteriorates and unevennessif formed. In recent high density media, because the floating amount ofa substrate and head is around 5 nm, it is necessary to form unevennesssmaller than 5 nm. That is, it is necessary to prevent the attachment offoreign material with a size of ≦5 nm. This is also true for a damageduneven surface. Consequently, it is possible to the inspection device ofthe present invention to an inspection of this foreign material ordamage and an inspection at a high speed and sensitivity is possible.Furthermore, the principles, effects and operations are the same asdescribe above.

In addition, when defects are produced when forming a substrate, forexample, when a protective film contains a pin hole or when thecomponents of a magnetic film are not uniform, a negative uniformity ofa potential distribution on a film is sometimes produced. For example, auniform surface potential is obtained if the surface is uniform when aconstant charge is provided to a substrate surface with relativelylittle damage, however, when a protective film contains a pin hole orwhen the components of a magnetic film are not uniform, the surfacepotential becomes non-uniform. At this time, it is possible to observeand measure a quantity ratio of mirror electrons and secondary emissionelectrons corresponding to the surface potential by increasingresolution (reducing Px size) and performing an inspection. That is, achange in a quantity ratio of electrons at a certain uniform part is lowwhen a cell/cell inspection is performed, however, since a difference inthe quantity ratio is produced when such parts are non-uniform, it ispossible to detect these as defects.

While the method and means are not limited to that described above, adefect inspection of a HDD substrate is possible using the method anddevice of the present invention. This inspection can be performed at ahigher speed and sensitivity compared to the conventional technology.This is because the object defects become ultrafine and thereforesensitivity in an optical type inspection device is insufficient and alarge amount of time is required in a SEM with a high resolution.

In addition, a defect inspection in a manufacturing process of amagnetic head is similarly possible. Because the same processes areperformed in manufacturing a magnetic head as in a manufacturing processof a semiconductor wafer, an inspection of defects such as shape defectsor film quality defects can be performed efficiently as describe above.Furthermore, the present embodiment can be applied to the embodiments1˜35 and also to embodiments with no number attached.

Thirty Seventh Embodiment Stage Device

A stage device used in the inspection device and inspection method ofthe present invention is explained.

The structure of a stage device is shown in FIG. 195A, FIG. 196B.

As shown in FIG. 195A, FIG. 196B, the stage device 1 of the inspectiondevice of the present invention is arranged with a Y axis base disc 2arranged on a bottom wall of a housing 4, a Y stage 5 and which moves ina Y axis direction using a guide rail 3 arranged parallel in the Y axisdirection on the Y axis base disc 2, and a mask plate 8 mounted and an Xstate 7 and movable in the XY directions using the X stage 7 which movesin the X direction using a an X guide rail 6 arranged in the Y axisdirection and parallel in the X direction of the perpendiculardirection. The main function of the stage device 1 is an inspection of amask 22 mounted on the mask plate 8 by moving the mask 22 within adefined region by repeating operations of a scan movement in the X axisdirection using the X stage 7 and a step movement in the Y axisdirection using the Y state 5 with respect an electron beam inspectionlight 26 which is irradiated from a column 21 of an electron opticalsystem device. The X stage 7 is scan moved in the X axis directionaccording to a movement distance and speed which accompanies a definedmovement direction and the Y stage 5 is step moved in the Y axisdirection according to a movement distance and a defined movementdirection. Here, the mask 22 is fixed on a palette (not shown in thediagram) and the palette is fixed by an electrostatic chuck (not shownin the diagram) attached to the mask plate 8. In addition, the housing 4in which the stage device 1 is arranged is set on a surface of a fixedplate 24 supported by 4 vibration isolation tables 23 and thus theeffects of external vibration from the floor 25 is reduced. In addition,the stage device 1 is covered by the housing 4 and operates in aperiphery atmosphere with a vacuum level of around 10⁻⁴ Pa. Therefore, adrive system X servomotor 9 and Y servomotor 11 are arranged on theexterior of the housing 4 in order to prevent gas emission, heatemission and dust emission. The X stage 7 and Y stage 5 are driven viaan X power transmission shaft 10, and Y power transmission shaft 12which form a side wall and vacuum shield of the housing 4, and anencoder 27 is used for control management of the X servomotor 9 and anencoder 28 is used for control management of the Y servomotor 11. Inaddition, a laser interferometer system is used to measure the locationof the mask palette 8 mounted with the mask 22. A laser interferometersystem comprised from an X stage mirror 19 and X interferometer 13arranged on the X axis side of the mask palette 8, an X interferometerbase 15 for supporting the X interferometer 13, a Y stage mirror 20 andY interferometer 14 arranged on the Y axis side, a Y interferometer base16 for supporting the Y interferometer 14, and optical parts such as alaser head (not shown in the diagram), and an AXIS board (not shown inthe diagram) for photoelectric signal conversion. Each location of the Xstage 7 and the Y stage 5 are measured with a high level of accuracy byan X length measurement beam 17 and Y length measurement beam 18. Astage control system (not shown in the diagram) performs positioning ofa state with a sub-micron level of accuracy by control feedback of eachaxis using a location signal in the XY axis directions obtained by thelaser interferometer system with respect to the drive system servomotor9 and Y servomotor 11.

In the present embodiment, a scan movement was set as the X axisdirection and the step movement was set as the Y axis direction of amask inspection, however, a scan movement may be set as the Y axisdirection and the step movement may be set as the X axis direction byalignment with the mask inspection direction. In addition, because thedrive system of the stage device 1 uses an electron beam inspectionlight, it is preferable to use non-magnetism. Therefore, a non-contacttype stage mechanism 1 may be a non-contact type. In this case, a stageguide rail is formed using a gas static pressure bearing using an airpressure drive mechanism or a differential exhaust method which supportsa vacuum atmosphere.

Thirty Eighth Embodiment Laser Irradiation Location Control

For example, in the structure shown in FIG. 35, it is necessary toirradiate the spot center of a laser to a predetermined location of aphotoelectron surface 2021. This is because electrons (photoelectrons)are generated from this spot location and thus this location becomes anelectron generation location. The electrons (photoelectrons) emittedfrom this location are irradiated to a sample surface after passingthrough a primary system. At this time, when electrons (photoelectrons)are irradiated to a lens it is necessary for the electrons to passthrough the center of the lens. This is because the trajectory of theelectrons (photoelectrons) becomes curved when misaligned from the lenscenter. When this trajectory curve is large, the electrons(photoelectrons) collide with a column wall, and it is sometimes nolonger possible to correct the trajectory using an aligner (deflector)when the curve exceeds a trajectory correction range. When there is notaligner between a lens and a photoelectron generation part, thetrajectory of the photoelectrons which pass through a lens is determinedby the location of the photoelectron generation part. That is, when alaser is irradiated to a misaligned location and photoelectrons aregenerated from a misaligned location, the electron beam does not passthrough the center of the lens.

In the present embodiment, a structure which can irradiate a laser spotcenter to a predetermined location of a photoelectron surface 2021 isshown in FIG. 35 in order to solve this problem. Referring to FIG. 199,as is shown in the exemplary view of a cross section of thephotoelectron surface 2021 in FIG. 199 (a), the photoelectron surface2021 is arranged with a base material 20211, a photoelectron material20212, a conducting material 20213, a support part 20214 and a laserirradiation aperture 20215. The base material 20211 is a lighttransmittance part such as quartz, silica glass, Koltz glass, ormagnesium fluoride glass. A material having a low work function (amaterial with a good photoelectron generation efficiency) such asRuthenium or Gold is preferably used as the photoelectron material20212, and is coated on the base 20211. A material with a lowconductivity such as chrome is preferably used as the conductingmaterial 21213. The support part 20214 is formed form a conductivematerial and supports the base material 20211. As is shown in FIG. 199(a), the photoelectron material 20212, conductive material 20213 andsupport part 20214 are electrically connected. The laser irradiationaperture 20215 may also be electrically connected to these parts.

A reflective material such as molybdenum or tantalum is preferably usedas the laser irradiation aperture 20215, and is arranged on the laserirradiation side of the base material 20211. A material having a goodsurface roughness for strengthening (increasing) the reflectanceintensity of a laser is preferred to be used for the surface of thelaser irradiation aperture 20215, for example, mirror surface polishing,or a surface roughness of 1 um or less is preferred. In addition, inthis example, as is shown in the upper surface diagram of the laserirradiation aperture 20215 in FIG. 199 (a), the laser irradiationaperture 20215 is arranged with an interior diameter region 20216 with adiameter d2 a center part of a round disc shape part having a diameterd1 (about 3˜5 mm). When an irradiated laser is reflected by the laserirradiation aperture 20215, the reflectance intensity of the reflectedlight becomes stronger than the reflectance intensity of a reflectancelight reflected by a photoelectron material 20212 described next. On theother hand, when a laser passes through the interior diameter region20216 and is reflected by the photoelectron material 20212, thereflectance intensity of this reflected light becomes weaker than thewhen reflected by the laser irradiation aperture 20215. Furthermore, thereflected light intensity may be measured by an actinometer arranged onthe reflected light path.

A DUV laser, for example, a laser with a wavelength of 266 nm or 244 nmcan be used as the laser. It is possible to use a solid-state laser orgas laser. It is also possible to use a lamp light which generates awavelength of 270 nm or less. For example, a high harmonic laser with a4 or 5 harmony of a YAG laser can be used as the solid-state laser. Inaddition, an Ar ion laser or excimer laser can be used as the gas laser.

The laser passes through the interior diameter region 20126 of the laserirradiation aperture 20215, reaches the photoelectron material 20212 andphotoelectrons are generated. The laser irradiation location is moved inan X direction from the state (for example, first the laser irradiationlocation is appropriately changed and from a change in the reflectanceintensity shown below, the laser irradiation location which becomes theinterior diameter region 20216 is calculated) in the interior diameterregion 20216 by controlling an optical system such as a mirror iscontrolled with control system. When the laser irradiation locationreaches an end part (interior diameter side end part of the laserirradiation aperture 20215) of the interior diameter region 20216, as isshown in FIG. 199 (c), the reflectance intensity measured by anactinometer etc rises. This end part location (x1, y1) is stored by acontrol system. An optical system such as a mirror is controlled by acontrol system and the irradiation location is moved in a −X direction.When the laser irradiation location reaches an end part (interiordiameter side end part of the laser irradiation aperture 20215) of theopposite side of interior diameter region 20216, the reflectance lightintensity measured by an actinometer etc rises. This end part location(x2, y2) is stored by a control system. Using this operation, the amountof mirror angle movement when moving from (x1, y1) to (x2, y2) is storedby a control system. In the example shown in FIG. 199 (c), (x1, y1)corresponds to PL and (x2, y2) corresponds to PR. Coordinate movementamount per minimum memory (minimum adjustment amount or control amount)of a mirror movement adjustment is calculated by a control system. Xdirection is Δx and the y direction is Δy, for example, 5 μm etc perminimum adjustment amount (memory).

At this time, the coordinates of 4 places on end parts of the interiordiameter side of the laser irradiation aperture 20215 are stored by acontrol system. For example, coordinates of a vertical and horizontallocation (PL, PR, PU, PD) are stored. In this way, the center C (0, 0)of the interior diameter region 20216 is determined. Furthermore, not bythe coordinates PL, PR, PU, PD but the center C (0, 0) is determined iftwo end part coordinates are calculated when an irradiation location ismoved in an x direction and two end part coordinates are calculated whenan irradiation location is moved in a y direction. When the two placecoordinates in an x direction are (xa, y0), (xb, y0) and the two placecoordinates in a y direction are (x0, ya), (x0, yb), the center C can bedetermined as (xa+xb)/2, (ya+yb)/2.

Following this, within the interior diameter region 20216, that is, at alocation within these four coordinates, the laser irradiation locationof an electron beam which passes through a lens center, that is, thecoordinates of a location P (x, y) of the photoelectron material 20212on the lens center axis can be confirmed by a control system. In thisway, the control system can ascertain a laser irradiation location, thatis, the coordinates of an irradiation location are calculated andstored. In this way, even if the location relationship of a laser,mirror or lens (photoelectron generation device 2020) changes, thecontrol system can irradiate a laser again to a location P (x, y). Thislaser irradiation location control is performed before inspecting asample. Furthermore, the present embodiment can be applied to theembodiments 1˜37 and also to embodiments with no number attached.

In addition, the photoelectron surface 2021 may have a differentstructure such as the structure shown in FIG. 200. The location side ofthe photoelectron material 20212 of the base material 20211 shown inFIG. 199 (a) has a shape which a difference in levels for beingsupported by the support part 20214. However, in the example of FIG. 200in the present embodiment this is a planar surface. In addition, thesupport part 20214 supports the base material 20211 so that it issandwiched from both sides using a part 20217 such as a screw.

Thirty Ninth Embodiment Axis Adjustment of a Primary System

As described in the thirty eighth embodiment above, a method for settingthe trajectory of an electron beam so that it passes through the centerof a lens when a laser irradiation location is adjusted to a location P(x, y) is explained. For example, in the photoelectron generation device2020 shown in FIG. 35, even if the power (lens power) of lens 2022, 2023and 2024 is changed as is shown in EB1 of FIG. 201 in the case where thetrajectory of an electron beam passes through the center of a lens, thetrajectory of an electron beam after passing through the lens does notchange. On the other hand, when a lens power is changed in the casewhere the trajectory of an electron beam passes through a locationmisaligned from the center of a lens, as is shown in EB2, EB3 of FIG.201, the trajectory of the electron beam after passing through the lenschanges. The structure in the present embodiment utilizes thesecharacteristics.

The photoelectron device 2020 of the present embodiment shown in FIG.201 is the same as that shown in FIG. 35. A measurement is performedusing an aperture 2040 and aligner 2030.

Any of a plurality of aligners 2031, 2032, 2033 which comprised thealigner 2030 may be used. (at this time, a large size that does notcause measurement problems may be used for the numerical aperture 2025,for example, φ500˜φ2000 μm). The measurement aperture 2040 is formed sothat an absorption current produced as a result of irradiating anelectron beam can be measured.

The trajectory of an electron beam is controlled by a control system sothat a deflected amount of (for example, deflection voltage or currentrequired for deflection) which becomes an opposite side end part from anend part of a hole in the measurement aligner 2024 is calculated usingthe aligner 2030 (2031 for example in FIG. 35). That is, as is shown inFIG. 201, the deflection voltage of the aligner is changed and thetrajectory of the electron beam is misaligned so that a state (EB3)where the trajectory of the electron beam is irradiated to themeasurement aperture 2040 (electron beam does not pass through the holeof the measurement aligner 2040), then a state (EB1, EB2) where thetrajectory of the electron beam passes through the hole of themeasurement aperture 2040, and a state (EB4) where the trajectory of theelectron beam is irradiated to the measurement aperture 2040 again, andthe absorption current of the measurement aperture 2040 with respect tothe deflection voltage of the aligner 2030 is measured. When thismeasurement is performed, as is shown in FIG. 202, the absorptioncurrent at the measurement aperture 2040 is measured changing [electronbeam entire amount absorption (large absorption current)] to [reducedelectron beam absorption passing through the hole (small absorptioncurrent)] to [electron beam entire amount absorption (large absorptioncurrent)]. This is performed by changing a plurality of lens powers (GLpower).

As is shown in FIG. 202 (a), in a large, small GL power, if thedeflection amount (a BA voltage where the absorption current becomesminimum (deflection voltage, the same below)) where the absorptioncurrent is reduced the most is the same, the electron beam has atrajectory which passes through the center of a hole of the measurementaperture 2040. On the other hand, as is shown in FIG. 202 (b), in alarge, small GL power, the electron beam trajectory is misaligned fromthe center of a lens in the case where the BA voltage where theabsorption current becomes minimum. While the control system changes thelocation where a laser is irradiated, in a large, small GL power, thelocation where the BA voltage where the absorption current becomesminimum becomes the same voltage, that is, the location of laserirradiation of an electron beam trajectory which passes through thecenter of lens is calculated, and these coordinates are stored as thelaser irradiation location P (x, y) of an electron beam trajectory.Furthermore, the present embodiment can be applied to the embodiments1˜38 and also to embodiments with no number attached.

Fortieth Embodiment Laser Irradiation Size Control

As described in embodiments 38, 39 above, in addition to control of anirradiation location of a laser irradiated to a photoelectron surface2021, the irradiation size (spot diameter) of a laser is an importantparameter for influencing the size of an electron beam irradiated to asample. In an adjustment of a spot diameter, the laser output from alight source may not be adjusted to a desired size simply using a lensand mirror. A spot diameter 2ω₀ is expressed as 2ω₀=(4λ/λ) (F/D). Here,λ is a light wavelength, F is the focal distance of a lens, and D showsthe diameter of a laser at a lens location. As can be understood fromthis equation, a spot diameter is proportional to the focal distance,and disproportional to the diameter of the laser at the lens location.Therefore, in order to reduce the size of the spot diameter, there is amethod for increasing the diameter of a laser from a light source usinga beam expander and irradiating to a lens, and a method using a shortfocal point lens. A method for reducing the size of the spot diameter iseffective for appropriately adjusting an irradiation location of a laserand spot diameter by combining with a control method of the laserirradiation location described above.

An example in the case of using a beam expander is explained using FIG.203. As is shown in FIG. 203, a laser with a diameter of φd1 output froma light source 10000 is magnified by A times in a beam expander 810,becomes a laser with a of φd2, and is irradiated to a lens 820 with alens focal point F1. The laser is reflected by a mirror 830, passesthrough a transparent window 840 arranged on a vacuum container formaintaining a vacuum, and reaches the photoelectron material 20212 whichis arranged at a location corresponding to the lens focal point F1. Atthis time, the spot diameter of the laser at the photoelectron material20212 becomes at minimum 2ω₀=(4λ/λ) (F1/φd2). In this example, the laserhas a CW (continuous wave) of λ=266 nm. Furthermore, in the embodiment38, adjustment of the laser irradiation location may be performed bychanging the angle of the mirror 830. In addition, a movement mechanism825 which moves the lens 820 along an optical axis of a laser may alsobe arranged. When the lens 820 is moved by the movement mechanism 825 itis possible to change the spot diameter of a lens in the photoelectronmaterial 20212.

In the present example, the relationship between a lens focal distanceand minimum spot diameter with regards to the case where a beam expandedis arranged and the case where a beam expander is not arranged is shownin FIG. 204. As is shown in FIG. 204, the spot diameter increases thelonger the lens focal distance becomes, and in the case where a beamexpander is arranged, the spot diameter decreases in size compared towhen a beam expander is not arranged.

In addition, an example in the case where a shirt focal point lens isused between the mirror 830 and the vacuum container 850 is explainedusing FIG. 205. As is shown in FIG. 205, a laser with a diameter of φd1output from a light source 10000 is reflected by a mirror 830, and isirradiated to the lens 821 with a lens focal point F2. The laser passesthrough a transparent window 840 arranged on a vacuum container 850 formaintaining a vacuum, and reaches a photoelectron material 20212arranged at a location corresponding to the lens focal point F2.

Furthermore, a movement mechanism 825 for moving a laser 821 along anoptical axis of a laser may be arranged. When the lens 821 is moved bythe movement mechanism 825 it is possible to change the spot diameter ofa lens in the photoelectron material 20212. In addition, because thelens 821 has a short focal point, it is arranged more to thephotoelectron material 20212 side than the mirror 830. As a result, whenthe laser irradiation location is adjusted by the mirror 830, the laseris sometimes misaligned from the center of the lens 821. Therefore, inorder to correct this alignment, the movement mechanism 825 may move thelens 821 within a surface which makes an optical axis a normal line.Furthermore, the beam expander 810 (not shown in FIG. 205) explained inFIG. 203 may be combined and used.

In addition, it is possible to use a lens 822 having a shorter focalpoint F3 than the lens 821. Lens 820 and 821 are arranged on theatmosphere side of the exterior of the vacuum container 850. However, inthis case, as is shown in FIG. 206, the lens 822 may be arranged on theinterior of the vacuum container 850. The moving mechanism 825 may alsobe arranged on the lens 822. The beam expander 810 (not shown in FIG.205) explained in FIG. 203 may be combined and used even in this case.Furthermore, the present embodiment can be applied to the embodiments1˜39 and also to embodiments with no number attached.

Forty First Embodiment

In the photoelectron generation device 2020 shown in FIG. 35, astructure which adds an aligner after a lens group 2022, 2023, and 2024is explained using FIG. 207. In the present embodiment, an explanationof a structure which is the same as the structure shown in FIG. 35 isomitted. An aligner 2060 includes a first aligner 2061 and a secondaligner 2062. The aligner 2061 and second aligner 2062 are arrangedbetween a third stage lens 2024 and a numerical aperture 2065 andperforms a static operation the same as the first aligner 2031 andsecond aligner 2032. However, as stated above, the first aligner 2031and second aligner 2032 are used for controlling an irradiation locationof an electron beam to a sample, while the first aligner 2061 and thesecond aligner 2062 are used for control so that the electron beampasses through the center of a hole of the numerical aperture 2025.Furthermore, the present embodiment can be applied to the embodiments1˜40 and also to embodiments with no number attached.

Forty Second Embodiment

Photoelectron surface primary system with a zoom function

It is possible to provide the structure shown in FIG. 35 and FIG. 207with a zoom function which controls the size of an electron beamirradiated to a sample. Here, the case where the structure of FIG. 207explained in embodiment 41 is provided with a zoom function is explainedusing FIG. 208. In the present embodiment, an explanation of the samestructure as that shown in FIG. 207 is omitted.

The structure shown in FIG. 208 includes a lens group 2091, 2092 and2093 (forming one lens from 3 electrodes) arranged between a numericalaperture 2025 and first aligner 2031 in addition to the structure shownin FIG. 207. In FIG. 35, FIG. 207 and FIG. 208, the electrodes 2022,2023 and 2024 form one group lens. In this embodiment in FIG. 208, lens2022, 2023 and 2024 are called EL1 (Electrostatic Lens), lens 2091, 2092and 2093 are called EL2, the aligner 2060 is called aligner 1, and thealigner 2030 is called aligner 2. Furthermore, a numerical aperture maybe arranged between the lens 2093 and the first aligner 2031. In thiscase, a primary optical system 2000 includes two numerical apertures.

By adopting the zoom lens structure of the present embodiment it ispossible to control the size of an electron beam irradiated to a sample.It is possible to control the size of an electron beam irradiated to asample by a zoom function using EL1 and EL2 with the same conditions asthe irradiation size of a laser irradiated to a photoelectron surface2021. For example, control of ×0.1˜×30 with respect to a size of a laserirradiated to the photoelectron surface 2021 is possible.

It is necessary to changing the size of an electron beam on a samplesurface with respect to the magnification of a secondary system (opticalsystem which forms an electron image of a sample). When themagnification of secondary system varies, the size of a field of view ona sample surface (region imaged as an electron image by a detector)changes. As a result, it is necessary to change the size of an electronbeam with respect to a variation in magnification. For example, when thefield of view is changed from 30×15 μm to 200×100 μm, it is alsonecessary to change to a size which also covers the size of an electronbeam, for example, it is necessary to change the electron beamirradiated with a 60×30 μm elliptical or rectangular shape to anelectron beam with a 300×150 μm elliptical or rectangular shape.

At this time, it is possible to be compatible with a change inirradiation size of laser in a photoelectron surface 2021, it isnecessary to replace or adjust a laser system in order to change anirradiation size of a laser which takes time, and when a small spotdiameter of a laser is formed corresponding to a small field of view,the laser density changes and a change in the amount of photoelectronsis produced. In addition, instability is sometimes produced in theamount of photoelectrons. At this time, when a zoom function of aprimary system described above is used, it is possible to control anirradiation region of an electron beam on a sample surface even with thesame laser irradiation size. Therefore, this structure which has thiszoom function is very effective.

The structure in this embodiment is an example of arranging 2 aligners,aligner 1 and aligner 2. The aligner 1 is used for passing thetrajectory of an electron beam through the center of the numericalaperture 2025 and EL2. The aligner may also be used by combining withthe aligner in the secondary system with respect to the lens center.

An example of a voltage applied to each structural element shown in FIG.208 is shown. A voltage of the photoelectron surface 2021 is given asV1, a voltage of electrodes which form an extraction lens are each givenas follows, a voltage of a first extraction electrode 2022 is V2, avoltage of a second extraction electrode 2023 is V3, a voltage of athird extraction electrode 2024 is V4 (here, the structure of electrodes2022, 2023, 2034 form one electrostatic lens), a voltage of thenumerical aperture 2025 is V5, a voltage of a third aligner 2033 is V6,a voltage of a lens electrode 2091 is V6, a voltage of a lens electrode2092 is V7, a voltage of a lens electrode 2093 is V8, and a voltage ofan aperture 2040 is V9. In addition, a surface voltage of a wafer isgiven as RTD (also called a retarded voltage). In a primary opticalsystem 2000 of the present embodiment, when described based on thevoltage V1 of the photoelectron surface 2021, the voltages applied toeach structural element are as follows. That is, in the case of a lowLE, V1=RTD−10V˜RTD+5V. V2, V4, V6, V8˜V1+3000˜30000V. V3,V7=V4+10000˜30000V. V5, V9=a reference voltage. In addition, RTD=−5000V,V1=−5005V, V2, V4, V6, V8=GND, V3=+20000V, V7=+17000V are set as anexample of a primary optical system in the present embodiment. It ispossible to realize a high resolution and high throughput at a low LEusing the voltage application described above. However, this is only anexample and the voltages applied to each of the structural elements arenot limited to this example. Furthermore, the present embodiment can beapplied to the embodiments 1˜41 and also to embodiments with no numberattached.

Forty Third Embodiment Discharge Prevention Spacer Shape

The distance between each lens extraction electrode such as lens 724 islimited. As a result, in the case where a side surface of a spacer of aconductor sandwiched between the electrodes is a planar shape (crosssection is a straight line shape), a creeping resistance is sometimesinsufficient. In this case, it is effective to use the structure shownin FIG. 209. In the example shown in FIG. 209, a spacer arranged betweenthe electrodes 7241, 7242 has a structure where 3 spacers having aspinning top shape are linked and the surface has a wave shape. Inaddition, the spacer 7245 is formed from an insulator such as a ceramicwith a surface resistance of 10⁸˜10¹² Ω·cm, and a charge up is reducedby the flow of a small leak current. Furthermore, the spinning topshaped spacers are not limited to 3, and 4˜12 may be used.

In the case where a creeping dielectric strength voltage isinsufficient, for example, a value of 1 kV/mm or more (for example, inthe case where the potential difference of electrodes 7241, 7242 becomes20 kV, D=20 mm or less), the spacer 7245 with the shape in FIG. 209 (a)is used. The side surface has an uneven shape and the electric field ata creeping distance becomes 1.kV/mm or less. At this time, the surfaceof electrodes 7241, 7424 which connect, the spacer 7245 shown in FIG.209 (a) is connected at the hollow part and the spacer 7246 shown inFIG. 209 (b) is connected at the bump part.

At this time, discharge resistance is significantly different betweenthe spacer 7245 which is connected with the electrode at the hollow partand the spacer 7246 which is connected with the electrode at the bumppart. The spacer shown in FIG. 209 (a) is preferred. For example, whendischarge occurs at point a, L/d is large, discharge converges at ahollow part, and the possibility of a discharge occurring with theexterior decreases. This is because electrical field variation is smallat a hollow part, that is, because of the same potential space,electrons fly to the exterior. Consequently, a stable state is obtainedwhere discharge between electrodes is difficult to occur. However,because the spacer 7246 shown in FIG. 209 (b) is connected with theelectrodes 7421 and 7242 at the bump part, when discharge occurs atpoint b, discharge with the exterior of the spacer 7246 easily occurs.This is because the space on the exterior of the spacer 7246 isimmediately adjacent and therefore the possibility of electrons flyingto this space increases compared to the spacer 7245 shown in FIG. 209(a). In addition, even if discharge occurs near the point b, electronswhich are generated at this spot fly to the periphery and dischargeoccurs which is a large secondary cause. Usually, the possibility ofdischarge occurring at point a, point b is high, in this case partswhere a variation in potential is high. In the case of the spacer 7245shown in FIG. 209 (a), in particular, a large L/d is preferred. Forexample, when L/d≧4, discharge resistance is increased, and L/d≧4˜10 ispreferred in order to satisfy manufacturing possibilities.

The lens which uses this spacer 7245 is used in the structure shown inFIG. 209 (c). Furthermore, the present embodiment can be applied to theembodiments 1˜42 and also to embodiments with no number attached.

Forty Fourth Embodiment Contamination Prevention

As described in the embodiments 13, 27, a structure for preventingparticles can also take different structures. For example, as is shownin FIG. 210, a gap G for preventing discharge is sandwiched on theperiphery of the lens 724, and a shield barrier VB is often arranged.FIG. 210 (a) exemplary shows a cross section of a surface which passesthrough a center axis of the lens 724, and FIG. 210 (b) shows eachstructure of the lens 724 direction seen from the sample W. In thestructure shown in FIG. 210, when a high voltage is applied to the lens724, foreign materials are deposited on a surface (contamination regionCA) of a wafer W corresponding to the part of the gap G and therebybecomes contaminated,

Two types of structure (FIG. 211, FIG. 212) are explained in the presentembodiment as a method for preventing contamination. FIG. 211 (a), FIG.212 (a) are exemplary diagrams which shows a cross section at a surfacewhich passes through a center of the lens 724, FIG. 211 (b), FIG. 212(b) are diagrams which shows each structure in the case of viewing thelens 724 direction seen from the sample W.

The example of a first structure is a structure which blocks a gap G bya round disc shaped insulator shield IS1 which has an open center as isshown in FIG. 211. The insulator IS1 is formed from ceramic or SiO₂ etc,and is formed to block the gap G by attaching to the voltage shieldbarrier VB. In this example, the insulator IS1 is attached to the sampleW side of the voltage shield barrier VB. Furthermore, without completelyblocking the gap with the insulator IS1, a gap may be arranged betweenthe gap and insulator IS1 with so that the gap G is narrower. In thisway, by arranging the insulator shield IS1 so that the gap is blocked orbecomes more narrow, it is possible to remove or reduce the depositionof foreign material on the contamination region CA of the sample W.

An example of a second structure is a structure where a cylinder shapedinsulator IS2 is arranged so as to enclose the lens 724 as is shown inFIG. 212. The insulator shield IS2 is formed from ceramic or SiO₂ and isfixed to the lens 724. A thermal expansion rate is different the betweenthe insulator shield IS2 and the lens 724. Using this difference in thethermal expansion rate, the insulator shield 724 is inserted aftercooling the lens 724, and the insulator shield IS2 and the lens 724 arefixed using a cooling fit when the lens 724 returns to a normaltemperature. Fixing with a screw etc leads to a decrease in positioningaccuracy due to tolerance, however, positioning of a center axis of alens becomes easier when fixing as in the present embodiment.

Because a foreign material is electrically controlled using theinsulator shield IS2 from reaching a sample due to the effects of anelectric field from the lens 724 with this structure, it I possible toremove or reduce foreign material deposited on a contamination region CAof the sample W. Furthermore, a small leak current flows when both theinsulator IS1 and IS2 have a surface resistance of 10⁸˜10¹² Ω·cm, and itis possible to reduce a charge up. Furthermore, the present embodimentcan be applied to the embodiments 1˜43 and also to embodiments with nonumber attached.

Forty Fifth Embodiment Discharge Prevention

Location control of a stage device 50 as described above is performed bythe structure in FIG. 213 when a laser interferometer ranging device isused. The potential relationship of each structure of the lens 724 andstage device 50 is shown in FIG. 213 (a) when viewed from a side surfacedirection and in FIG. 213 (b) when viewed from an upper surfacedirection. A laser interferometer mirror 510 x for controlling thelocation of an x axis direction and a laser interferometer mirror 510 yfor controlling the location of a y axis direction are arranged in thestage device 50. A laser is irradiated from a laser interferometer 511 xto the laser interferometer mirror 510 x, and a laser is irradiated froma laser interferometer 511 y to the laser interferometer mirror 510 y.

It is preferred that the laser interferometer mirror 510 x and 510 yreflect a laser at the same height (location of a surface of a sample W)as a sample W. This is because the greater the difference in height withthe sample W, the larger the error in a measurement location is producedas is shown from the Abbe principle. As is shown in Fig, in the casewhere the laser interferometer mirror 510 x leans by φ, the error at alocation of a laser b becomes an (Hb-Hw) X tan φ. (Hb-Hw) is adifference between the height Hb of the laser b and the height Hw of thesample W. If φ is very small, tan φ≈φ. As a result, the greater thedifference (Hb-Hw) between the height Hb of the laser b and the heightHw of the sample W, the greater the error. Therefore, it is preferredthat the difference (Hb-Hw) between the height Hb of the laser b and theheight Hw of the sample W=0, that is, a laser a is irradiated to thelaser interferometer mirror 510 x at the height of the sample W.

Consequently, it is necessary that the laser interferometer mirror 510 xand 510 y are higher than the height Hw of the sample W. This isbecause, in particular, in the case where ceramic is used for the laserinterferometer mirror 510 x and 510 y in order to improve assemblyaccuracy, a ceramic surface is formed as a mirror by a mirror finish. Inthis case, several mm (for example, 3 mm) from an upper end partrequires an area outside specifications due to the demands whenmanufacturing. As is shown in FIG. 215, the height Hr of the laserinterferometer mirror 510 x, 510 y is required to be longer than theheight Hw (height of a sample W (location of the surface of the sample)irradiated with a laser, for example, by 3 mm. In addition, the distancebetween a surface of the sample W and the column lowest electrode 72D isa distance determined when designing the optics and in the presentembodiment is 4 mm. Therefore, the distance between the column lowestelectrode 72D and the laser interferometer mirror 510 x and 510 y is 1mm. As a result, depending on the location of the stage device 50, theupper end part of the laser interferometer mirror 510 x and 510 yapproaches to close to the lens 724 which is applied with a high voltageand electrical discharge often occurs. Therefore, it is necessary todetermine the location of the stage device 50 so that this dischargedoes not occur.

As is exemplary shown in FIG. 216 seen from the side surface, the columnlowest electrode 72D is fixed via the insulator IS to the lens 724 whichis applied with a high voltage (20 kV in this example), and is grounded(GND). A set value of breakdown field strength in the present embodimentis set at 4 kV/mm. As a result, it is necessary that the stage device50, sample W, the laser interferometer mirror 510 x and 510 y (inparticular, the laser interferometer mirror) do not enter within a rangeof 5 mm from a lower end part of the lens 724 which is applied with a 20kV voltage as shown in FIG. 216.

Thus, as is exemplary shown in FIG. 217 seen from the upper surface, ifa state whereby a gap Gd in a horizontal direction is not separated by4.58 mm or more from the lens 724 up to the laser interferometer mirror510 x, 510 y, an electrical field of 4 kV/mm or more is produced. As aresult, a movable range of the stage device 50 is controlled within arange where the gap Gd is 4.58 mm or more, and the location of the stagedevice 50 is controlled within this movable range. The example shown inFIG. 217 is a state where the stage device 50 is at its closest to thelaser interferometer mirror 511 x, 511 y within a range where the gap Gdis 4.58 mm or more. That is, when a wafer W is received from the loadingchamber 40 to the stage device 50 within the main housing 30, or whenthe sample W is received to the loading chamber 40 from the stage device50 within the main housing 30, the stage device 50 location is moved toa location (the position which becomes a movable range) where the upperpart of the laser interferometer does not discharge due to a lens.Because it is necessary to receive the sample W at the location of thestage device shown in FIG. 217 (the wall side facing the wall sidearranged laser interferometer mirror 510 x, 510 y in the main housing30), it is necessary to arrange a shutter device 45 which becomes anentrance and exit with the loading chamber 40 on either of 2 placesshown in FIG. 217 (the wall side facing the wall side arranged laserinterferometer mirror 510 x, 510 y in the main housing 30). Furthermore,the present embodiment can be applied to the embodiments 1˜44 and alsoto embodiments with no number attached.

Forty Sixth Embodiment

A type of light source 10000 of a light irradiated to a photoelectronsurface 2021 was described above however other light sources may beused. For example, a FUV lamp, excimer lamp, deuterium lamp or xenonlamp may be used. In addition, an LD excitation light source lamp may beused in which a LD (laser diode) is condensed and a spot plasma isformed and the light excited. The excitation light may be introduced tothe photoelectron surface 2021 using at least one of a lens or a mirror.In addition, this excitation light may be introduced to a fiber optic byat least one of a lens of a mirror, and introduced to the photoelectronsurface 2021 from the fiber optic. In addition, control of the plasmamay be performed using a magnetic field. Furthermore, the presentembodiment can be applied to the embodiments 1˜45 and also toembodiments with no number attached.

Forty Seventh Embodiment

In the explanation in FIG. 161, an example where an EB-TDI is used inthe detector system 70 is explained. However, other structures where aTDI is used are explained. In the present embodiment, an explanation ofthe same structure as in FIG. 161 is omitted.

First, a detector system 70 shown in FIG. 161 has a structure wherebyEB-CDD 71 is moved to a location away from an optical axis by a movementmechanism M in the case of using an EB-TDI 72. However, as a firstexample, a rotation shaft S may be linked to the movement mechanism M isshown in FIG. 218. In FIG. 218 (a), one end of the rotation shaft S isliked to one end of the plate shaped EB-CCD 71 which is loaded withnecessary circuits or substrate etc and the other end of the rotationshaft S is linked to the movement mechanism M. FIG. 218 (b), (c), arediagrams of the structure shown in FIG. 218 (a) seen from the movementmechanism direction. In the case where EB-CDD 73 is used, as is shown inFIG. 218 (b), an electron beam e is irradiated to the EB-CCD 73, and asensor surface of EB-CDD 73 is moved to become perpendicular to theelectron beam e. On the other hand, in the case where EB-TDI 72 is used,as is shown in FIG. 218 (c), the rotation shaft 21 is rotated by themovement mechanism M, and the EB-CCD 73 is moved to be parallel with anoptical axis of an electron optical system. Therefore, the electron beame is not irradiates to the EB-CCD 73 but to the EB-TDI 72.

The movement mechanism M which uses rotation shown in FIG. 218 has themerit of being able to reduce size and weight to ½˜ 1/10 compared to themovement mechanism which uses movement in a 1 axis direction explainedin FIG. 161.

As a second example, the detector system 70 is not formed by the EB-TDI72 but by a TDI sensor 721, FOP 722, fluorescent plate 723 and MCP 724in one package as is shown in FIG. 219. An output pin of the TDI sensor721 is connected to a pin 73 of a feed through FT using bonding or someother connection means. In this case, as described above, the MCP 724performs multiplication of the amount of detection electrons, and thefluorescent plate 723 converts the electrons to an optical signal. Thetwo dimensional optical signal is transmitted by the FOP 722, an imageis formed at the TDI sensor 721 and the signal is detected. In FIG. 219,the movement mechanism M was described in both the case a where theEB-CDD 71 is rotated and the case b where the EB-CDD 71 is moved to alocation away from the optical axis of an electron beam, however, eithercase may be adopted. FIG. 219 (a), (c) are diagrams of the structureshown in FIG. 219 (a) in the case where the movement mechanism M rotatesthe EB-CCD 71 is adopted seen from the movement mechanism M.Furthermore, the MCP 724 is no longer used in the detection system 70 inthe case where electron amplification is not required, as is shown inFIG. 220.

In addition, the detection system 70 may have a structure whereby thestructure where the EB-TDI 72 shown in FIG. 221 (a) is used and thestructure where the EB-CDD 71 shown in FIG. 221 (b) is used areswitched. At this time, the detector system 70 may have the structureshown in FIG. 222 (a) or the structure shown in FIG. 222 (b) instead ofthe structure where the EB-TDI 72 shown in FIG. 221 (a) is used.

The operation of the EB-TDI 72 is explained. FIG. 223 is a planardiagram which shows pixels P₁₁˜P_(ij) in the sensor surface 72S of theEB-TDI 72. In the same diagram, the arrow T1 shows an accumulationdirection of the sensor surface 72S, and T2 shows a perpendiculardirection to the accumulation direction T1, that is, a continuousmovement direction of the stage device 50. In the present embodiment,the pixels P₁₁˜P_(ij) in the ED-TDI 72 are arranged as follows; 500(number of accumulation stages i=500) pixels are arranged in theaccumulation direction T1, and 4000 (j=4000) pixels are arranged in thecontinuous movement direction T2 of the stage device 50.

FIG. 224 is a diagram which approximately shows the locationrelationship between the EB-TDI 72 and secondary charge particles. InFIG. 224, when secondary charge particles EB emitted from the sample Ware emitted from the same place of the sample Win a certain period oftime, the secondary charge particles EB are irradiated in sequence froma to i with respect to a series of spots a, b, c, d, e . . . i, on aprojection type optical system MO together with the continuous movementof the stage device 50. The secondary charge particles EB irradiated toprojection type optical system MO are irradiated in sequence A, B, C, D,E . . . I which are a series of spots on the projection type opticalsystem MO. At this time, when the charge accumulation movement to theaccumulation direction T1 of the EB-TDI 72 is synchronized with thecontinuous movement of the stage device 50, the secondary chargeparticles EB emitted from the spots A, B, C, D, E . . . I of theprojection type optical system MO are irradiated in sequence to the samespot on the sensor surface 72S, and it is possible to accumulate acharge for only the number of accumulation stages i. In this way, it ispossible to for each pixel P₁₁˜P_(ij) to obtain a signal with manyirradiation electrons, and therefore, a high S/N ratio can be realizedand a two dimensional electron image can be obtained at high speed. Theprojection type optical system MO has a magnification of 300 forexample.

The EB-CDD and EB-TDI described above have the followingcharacteristics.

(A) Gain is unambiguously determined using the irradiation energy of anelectron.(B) When the irradiation energy of an electron increases, sensor gainrises.(C) An effective sensor thickness (a thickness where electrons areeasily accumulated) is formed with respect to the irradiation energyband region of an electron. When the thickness is too thin, the amountof accumulated electrons is small, and when the thickness is too thick,it is difficult for electrons to accumulate.(D) A sensor which can directly irradiate electrons.(E) It is possible to use a back-illuminated type sensor as well as afront-illuminated type sensor.(F) It is possible to apply a voltage to a sensor surface (GND orconstant voltage).(G) A noise cut cover may be provided to a sensor periphery.(H) It is possible to make a voltage of at least one of a sensor andcamera a floating state (it is possible to make provide a referencepotential with an externally controllable structure).(I) Sensor gain=maximum accumulation charge amount/maximum obtainednumber of electrons.

Furthermore, the present embodiment can be applied to the embodiments1˜46 and also to embodiments with no number attached.

What is claimed is:
 1. An inspection device comprising: a lasergenerator generating a laser being irradiated to an inspection objectsupported within a working chamber; a secondary optical system having adetector detecting secondary charge particles generated from theinspection object irradiated with the laser; and an image processingsystem forming an image based on the secondary charge particles detectedby the detector.
 2. The inspection device according to claim 1, thedetector detecting the secondary charge particles generated from asurface opposite a surface of the inspection object irradiated with thelaser.
 3. The inspection device according to claim 1, the detectordetecting the secondary charge particles generated from a surface of theinspection object irradiated with the laser.
 4. The inspection deviceaccording to claim 3 further comprising: a primary optical systemguiding the laser generated by the laser generator to the inspectionobject.
 5. The inspection device according to claim 3 furthercomprising: a hollow fiber or a hollow pipe guiding the laser generatedby the laser generator to the inspection object.
 6. The inspectiondevice according to claim 1, the laser including wavelengths of eitherUV, DUV, EUV or X-ray.
 7. The inspection device according to claim 1,the laser generator having a first light source generating a firstwavelength laser and a second light source generating a secondwavelength laser.
 8. The inspection device according to claim 7, thefirst wavelength laser and the second wavelength laser being irradiatedto the inspection object alternately.
 9. The inspection device accordingto claim 1, the secondary optical system further having: a first lensaccelerating the secondary charge particles generated from theinspection object; a second lens group changing a magnification factorby converging the secondary accelerated charge particles and forming across over the numerical aperture; and a third lens forming an image ofthe secondary charge particles passing through the second lenses on thedetector.